diff --git a/libafl/benches/rand_speeds.rs b/libafl/benches/rand_speeds.rs
index ad97bd747b..486343d0cc 100644
--- a/libafl/benches/rand_speeds.rs
+++ b/libafl/benches/rand_speeds.rs
@@ -1,9 +1,9 @@
 //! Compare the speed of rand implementations
 
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
 use libafl::utils::{
     Lehmer64Rand, Rand, RomuDuoJrRand, RomuTrioRand, XorShift64Rand, Xoshiro256StarRand,
 };
-use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
 fn criterion_benchmark(c: &mut Criterion) {
     let mut xorshift = XorShift64Rand::new(1);
diff --git a/libafl/build.rs b/libafl/build.rs
index f77872e9a6..1c6e87c8ce 100644
--- a/libafl/build.rs
+++ b/libafl/build.rs
@@ -1,11 +1,9 @@
 fn main() {
-
-  #[cfg(target_os = "windows")]
-  windows::build!(
-      windows::win32::system_services::HANDLE,
-      windows::win32::windows_programming::CloseHandle,
-      // API needed for the shared memory
-      windows::win32::system_services::{CreateFileMappingA, OpenFileMappingA, MapViewOfFile, UnmapViewOfFile},
-  );
-
+    #[cfg(target_os = "windows")]
+    windows::build!(
+        windows::win32::system_services::HANDLE,
+        windows::win32::windows_programming::CloseHandle,
+        // API needed for the shared memory
+        windows::win32::system_services::{CreateFileMappingA, OpenFileMappingA, MapViewOfFile, UnmapViewOfFile},
+    );
 }
diff --git a/libafl/src/bolts/mod.rs b/libafl/src/bolts/mod.rs
index 099a20e799..f73268ce7c 100644
--- a/libafl/src/bolts/mod.rs
+++ b/libafl/src/bolts/mod.rs
@@ -1,8 +1,8 @@
 //! Bolts are no conceptual fuzzing elements, but they keep libafl-based fuzzers together.
 
+pub mod bindings;
 pub mod llmp;
 pub mod ownedref;
 pub mod serdeany;
 pub mod shmem;
 pub mod tuples;
-pub mod bindings;
diff --git a/libafl/src/bolts/serdeany.rs b/libafl/src/bolts/serdeany.rs
index d7cf5dc7e9..8fcd3ae208 100644
--- a/libafl/src/bolts/serdeany.rs
+++ b/libafl/src/bolts/serdeany.rs
@@ -512,7 +512,7 @@ macro_rules! impl_serdeany {
                 self
             }
         }
-        
+
         #[allow(non_snake_case)]
         #[cfg(feature = "std")]
         #[ctor]
diff --git a/libafl/src/bolts/shmem.rs b/libafl/src/bolts/shmem.rs
index 324f6d512a..cc4d4f962f 100644
--- a/libafl/src/bolts/shmem.rs
+++ b/libafl/src/bolts/shmem.rs
@@ -330,8 +330,8 @@ pub mod shmem {
     use core::{mem::size_of, slice};
     use std::ffi::CStr;
 
-    use crate::Error;
     use super::ShMem;
+    use crate::Error;
 
     /// The default Sharedmap impl for windows using shmctl & shmget
     #[derive(Clone, Debug)]
@@ -343,7 +343,6 @@ pub mod shmem {
     }
 
     // TODO complete
-
 }
 
 #[cfg(test)]
diff --git a/libafl/src/bolts/tuples.rs b/libafl/src/bolts/tuples.rs
index 2cd2d51d9e..ba20a0f29a 100644
--- a/libafl/src/bolts/tuples.rs
+++ b/libafl/src/bolts/tuples.rs
@@ -190,9 +190,9 @@ macro_rules! tuple_for_each {
             }
 
             impl ForEach for () {
-                fn for_each(&self) { }
+                fn for_each(&self) {}
             }
-            
+
             impl<Head, Tail> ForEach for (Head, Tail)
             where
                 Head: $trait_name,
@@ -206,7 +206,7 @@ macro_rules! tuple_for_each {
         }
         {
             use $fn_name::*;
-            
+
             $tuple_name.for_each();
         };
     };
@@ -221,9 +221,9 @@ macro_rules! tuple_for_each_mut {
             }
 
             impl ForEachMut for () {
-                fn for_each_mut(&mut self) { }
+                fn for_each_mut(&mut self) {}
             }
-            
+
             impl<Head, Tail> ForEachMut for (Head, Tail)
             where
                 Head: $trait_name,
@@ -237,7 +237,7 @@ macro_rules! tuple_for_each_mut {
         }
         {
             use $fn_name::*;
-            
+
             $tuple_name.for_each_mut();
         };
     };
@@ -245,13 +245,13 @@ macro_rules! tuple_for_each_mut {
 
 /*
 pub fn test_macros() {
-  
+
   let mut t = tuple_list!(1, "a");
 
   tuple_for_each!(f1, std::fmt::Display, t, |x| {
       println!("{}", x);
   });
-  
+
   tuple_for_each_mut!(f2, std::fmt::Display, t, |x| {
       println!("{}", x);
   });
diff --git a/libafl/src/corpus/mod.rs b/libafl/src/corpus/mod.rs
index 02493aa84b..32069c5f46 100644
--- a/libafl/src/corpus/mod.rs
+++ b/libafl/src/corpus/mod.rs
@@ -7,12 +7,7 @@ use alloc::vec::Vec;
 use core::cell::RefCell;
 use serde::{Deserialize, Serialize};
 
-use crate::{
-    inputs::Input,
-    state::{HasCorpus, HasRand},
-    utils::Rand,
-    Error,
-};
+use crate::{inputs::Input, Error};
 
 /// Corpus with all current testcases
 pub trait Corpus<I>: serde::Serialize + serde::de::DeserializeOwned
@@ -33,65 +28,41 @@ where
 
     /// Get by id
     fn get(&self, idx: usize) -> Result<&RefCell<Testcase<I>>, Error>;
+
+    /// Current testcase scheduled
+    fn current(&self) -> &Option<usize>;
+
+    /// Current testcase scheduled (mut)
+    fn current_mut(&mut self) -> &mut Option<usize>;
 }
 
-pub trait CorpusScheduler {
+pub trait CorpusScheduler<I, S>
+where
+    I: Input,
+{
     /// Add an entry to the corpus and return its index
-    fn on_add<C, I, R, S>(
-        &self,
-        state: &mut S,
-        idx: usize,
-        testcase: &Testcase<I>,
-    ) -> Result<(), Error>
-    where
-        S: HasCorpus<C, I> + HasRand<R>,
-        C: Corpus<I>,
-        I: Input,
-        R: Rand,
-    {
+    fn on_add(&self, state: &mut S, idx: usize, testcase: &Testcase<I>) -> Result<(), Error> {
         Ok(())
     }
 
     /// Replaces the testcase at the given idx
-    fn on_replace<C, I, R, S>(
-        &self,
-        state: &mut S,
-        idx: usize,
-        testcase: &Testcase<I>,
-    ) -> Result<(), Error>
-    where
-        S: HasCorpus<C, I> + HasRand<R>,
-        C: Corpus<I>,
-        I: Input,
-        R: Rand,
-    {
+    fn on_replace(&self, state: &mut S, idx: usize, testcase: &Testcase<I>) -> Result<(), Error> {
         Ok(())
     }
 
     /// Removes an entry from the corpus, returning it if it was present.
-    fn on_remove<C, I, R, S>(
+    fn on_remove(
         &self,
         state: &mut S,
         idx: usize,
         testcase: &Option<Testcase<I>>,
-    ) -> Result<(), Error>
-    where
-        S: HasCorpus<C, I> + HasRand<R>,
-        C: Corpus<I>,
-        I: Input,
-        R: Rand,
-    {
+    ) -> Result<(), Error> {
         Ok(())
     }
 
     // TODO: IntoIter
     /// Gets the next entry
-    fn next<C, I, R, S>(&self, state: &mut S) -> Result<usize, Error>
-    where
-        S: HasCorpus<C, I> + HasRand<R>,
-        C: Corpus<I>,
-        I: Input,
-        R: Rand;
+    fn next(&self, state: &mut S) -> Result<usize, Error>;
 }
 
 /*
@@ -124,6 +95,7 @@ where
     I: Input,
 {
     entries: Vec<RefCell<Testcase<I>>>,
+    current: Option<usize>,
 }
 
 impl<I> Corpus<I> for InMemoryCorpus<I>
@@ -168,4 +140,14 @@ where
     fn get(&self, idx: usize) -> Result<&RefCell<Testcase<I>>, Error> {
         Ok(&self.entries[idx])
     }
+
+    /// Current testcase scheduled
+    fn current(&self) -> &Option<usize> {
+        &self.current
+    }
+
+    /// Current testcase scheduled (mut)
+    fn current_mut(&mut self) -> &mut Option<usize> {
+        &mut self.current
+    }
 }
diff --git a/libafl/src/events/llmp.rs b/libafl/src/events/llmp.rs
index 27f6078ab3..2d7e82aaa8 100644
--- a/libafl/src/events/llmp.rs
+++ b/libafl/src/events/llmp.rs
@@ -39,23 +39,25 @@ const _LLMP_TAG_RESTART: llmp::Tag = 0x8357A87;
 const _LLMP_TAG_NO_RESTART: llmp::Tag = 0x57A7EE71;
 
 #[derive(Clone, Debug)]
-pub struct LlmpEventManager<I, SH, ST>
+pub struct LlmpEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
     //CE: CustomEvent<I>,
 {
     stats: Option<ST>,
     llmp: llmp::LlmpConnection<SH>,
-    phantom: PhantomData<I>,
+    phantom: PhantomData<(I, S)>,
 }
 
 #[cfg(feature = "std")]
 #[cfg(unix)]
-impl<I, ST> LlmpEventManager<I, UnixShMem, ST>
+impl<I, S, ST> LlmpEventManager<I, S, UnixShMem, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     ST: Stats,
 {
     /// Create llmp on a port
@@ -78,9 +80,10 @@ where
     }
 }
 
-impl<I, SH, ST> Drop for LlmpEventManager<I, SH, ST>
+impl<I, S, SH, ST> Drop for LlmpEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
 {
@@ -90,9 +93,10 @@ where
     }
 }
 
-impl<I, SH, ST> LlmpEventManager<I, SH, ST>
+impl<I, S, SH, ST> LlmpEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
 {
@@ -248,7 +252,7 @@ where
     }
 
     // Handle arriving events in the client
-    fn handle_in_client<E, OT, S>(
+    fn handle_in_client<E, OT>(
         &mut self,
         state: &mut S,
         sender_id: u32,
@@ -258,7 +262,6 @@ where
     where
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
-        S: IfInteresting<I>,
     {
         match event {
             Event::NewTestcase {
@@ -293,9 +296,10 @@ where
     }
 }
 
-impl<I, SH, ST> EventManager<E, I, S> for LlmpEventManager<I, SH, ST>
+impl<I, S, SH, ST> EventManager<I, S> for LlmpEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats, //CE: CustomEvent<I>,
 {
@@ -311,11 +315,10 @@ where
         }
     }
 
-    fn process<E, OT, S>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
+    fn process<E, OT>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
     where
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
-        S: IfInteresting<I>,
     {
         // TODO: Get around local event copy by moving handle_in_client
         let mut events = vec![];
@@ -344,7 +347,7 @@ where
         Ok(count)
     }
 
-    fn fire<S>(&mut self, _state: &mut S, event: Event<I>) -> Result<(), Error> {
+    fn fire(&mut self, _state: &mut S, event: Event<I>) -> Result<(), Error> {
         let serialized = postcard::to_allocvec(&event)?;
         self.llmp.send_buf(LLMP_TAG_EVENT_TO_BOTH, &serialized)?;
         Ok(())
@@ -356,11 +359,11 @@ where
 /// This method is needed when the fuzzer run crashes and has to restart.
 pub fn serialize_state_mgr<I, S, SH, ST>(
     state: &S,
-    mgr: &LlmpEventManager<I, SH, ST>,
+    mgr: &LlmpEventManager<I, S, SH, ST>,
 ) -> Result<Vec<u8>, Error>
 where
     I: Input,
-    S: Serialize,
+    S: Serialize + IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
 {
@@ -370,10 +373,10 @@ where
 /// Deserialize the state and corpus tuple, previously serialized with `serialize_state_corpus(...)`
 pub fn deserialize_state_mgr<I, S, SH, ST>(
     state_corpus_serialized: &[u8],
-) -> Result<(S, LlmpEventManager<I, SH, ST>), Error>
+) -> Result<(S, LlmpEventManager<I, S, SH, ST>), Error>
 where
     I: Input,
-    S: DeserializeOwned,
+    S: DeserializeOwned + IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
 {
@@ -386,22 +389,24 @@ where
 
 /// A manager that can restart on the fly, storing states in-between (in `on_resatrt`)
 #[derive(Clone, Debug)]
-pub struct LlmpRestartingEventManager<I, SH, ST>
+pub struct LlmpRestartingEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
     //CE: CustomEvent<I>,
 {
     /// The embedded llmp event manager
-    llmp_mgr: LlmpEventManager<I, SH, ST>,
+    llmp_mgr: LlmpEventManager<I, S, SH, ST>,
     /// The sender to serialize the state for the next runner
     sender: LlmpSender<SH>,
 }
 
-impl<I, SH, ST> EventManager<E, I, S> for LlmpRestartingEventManager<I, SH, ST>
+impl<I, S, SH, ST> EventManager<I, S> for LlmpRestartingEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I> + Serialize,
     SH: ShMem,
     ST: Stats, //CE: CustomEvent<I>,
 {
@@ -413,10 +418,7 @@ where
     }
 
     /// Reset the single page (we reuse it over and over from pos 0), then send the current state to the next runner.
-    fn on_restart<S>(&mut self, state: &mut S) -> Result<(), Error>
-    where
-        S: Serialize,
-    {
+    fn on_restart(&mut self, state: &mut S) -> Result<(), Error> {
         // First, reset the page to 0 so the next iteration can read read from the beginning of this page
         unsafe { self.sender.reset() };
         let state_corpus_serialized = serialize_state_mgr(state, &self.llmp_mgr)?;
@@ -424,16 +426,15 @@ where
             .send_buf(_LLMP_TAG_RESTART, &state_corpus_serialized)
     }
 
-    fn process<E, OT, S>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
+    fn process<E, OT>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
     where
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
-        S: IfInteresting<I>,
     {
         self.llmp_mgr.process(state, executor)
     }
 
-    fn fire<S>(&mut self, state: &mut S, event: Event<I>) -> Result<(), Error> {
+    fn fire(&mut self, state: &mut S, event: Event<I>) -> Result<(), Error> {
         // Check if we are going to crash in the event, in which case we store our current state for the next runner
         self.llmp_mgr.fire(state, event)
     }
@@ -445,14 +446,15 @@ const _ENV_FUZZER_RECEIVER: &str = &"_AFL_ENV_FUZZER_RECEIVER";
 /// The llmp (2 way) connection from a fuzzer to the broker (broadcasting all other fuzzer messages)
 const _ENV_FUZZER_BROKER_CLIENT_INITIAL: &str = &"_AFL_ENV_FUZZER_BROKER_CLIENT";
 
-impl<I, SH, ST> LlmpRestartingEventManager<I, SH, ST>
+impl<I, S, SH, ST> LlmpRestartingEventManager<I, S, SH, ST>
 where
     I: Input,
+    S: IfInteresting<I>,
     SH: ShMem,
     ST: Stats, //CE: CustomEvent<I>,
 {
     /// Create a new runner, the executed child doing the actual fuzzing.
-    pub fn new(llmp_mgr: LlmpEventManager<I, SH, ST>, sender: LlmpSender<SH>) -> Self {
+    pub fn new(llmp_mgr: LlmpEventManager<I, S, SH, ST>, sender: LlmpSender<SH>) -> Self {
         Self { llmp_mgr, sender }
     }
 
@@ -471,13 +473,13 @@ where
 /// The restarter will start a new process each time the child crashes or timeouts.
 #[cfg(feature = "std")]
 pub fn setup_restarting_mgr<I, S, SH, ST>(
-    //mgr: &mut LlmpEventManager<I, SH, ST>,
+    //mgr: &mut LlmpEventManager<I, S, SH, ST>,
     stats: ST,
     broker_port: u16,
-) -> Result<(Option<S>, LlmpRestartingEventManager<I, SH, ST>), Error>
+) -> Result<(Option<S>, LlmpRestartingEventManager<I, S, SH, ST>), Error>
 where
     I: Input,
-    S: DeserializeOwned,
+    S: DeserializeOwned + IfInteresting<I>,
     SH: ShMem,
     ST: Stats,
 {
@@ -485,7 +487,7 @@ where
 
     // We start ourself as child process to actually fuzz
     if std::env::var(_ENV_FUZZER_SENDER).is_err() {
-        mgr = LlmpEventManager::<I, SH, ST>::new_on_port(stats, broker_port)?;
+        mgr = LlmpEventManager::<I, S, SH, ST>::new_on_port(stats, broker_port)?;
         if mgr.is_broker() {
             // Yep, broker. Just loop here.
             println!("Doing broker things. Run this tool again to start fuzzing in a client.");
@@ -528,7 +530,7 @@ where
         None => {
             println!("First run. Let's set it all up");
             // Mgr to send and receive msgs from/to all other fuzzer instances
-            let client_mgr = LlmpEventManager::<I, SH, ST>::existing_client_from_env(
+            let client_mgr = LlmpEventManager::<I, S, SH, ST>::existing_client_from_env(
                 _ENV_FUZZER_BROKER_CLIENT_INITIAL,
             )?;
 
@@ -537,7 +539,7 @@ where
         // Restoring from a previous run, deserialize state and corpus.
         Some((_sender, _tag, msg)) => {
             println!("Subsequent run. Let's load all data from shmem (received {} bytes from previous instance)", msg.len());
-            let (state, mgr): (S, LlmpEventManager<I, SH, ST>) = deserialize_state_mgr(&msg)?;
+            let (state, mgr): (S, LlmpEventManager<I, S, SH, ST>) = deserialize_state_mgr(&msg)?;
 
             (Some(state), LlmpRestartingEventManager::new(mgr, sender))
         }
diff --git a/libafl/src/events/logger.rs b/libafl/src/events/logger.rs
index 0a37f9b8f2..4262d847a3 100644
--- a/libafl/src/events/logger.rs
+++ b/libafl/src/events/logger.rs
@@ -5,14 +5,16 @@ use core::marker::PhantomData;
 #[cfg(unix)]
 use crate::{
     events::{BrokerEventResult, Event, EventManager},
+    executors::{Executor, HasObservers},
     inputs::Input,
+    observers::ObserversTuple,
     stats::Stats,
     Error,
 };
 
 /// A simple, single-threaded event manager that just logs
 #[derive(Clone, Debug)]
-pub struct LoggerEventManager<E, I, S, ST>
+pub struct LoggerEventManager<I, S, ST>
 where
     I: Input,
     ST: Stats, //CE: CustomEvent<I, OT>,
@@ -21,15 +23,19 @@ where
     stats: ST,
     /// The events that happened since the last handle_in_broker
     events: Vec<Event<I>>,
-    phantom: PhantomData<(E, S)>,
+    phantom: PhantomData<S>,
 }
 
-impl<E, I, S, ST> EventManager<E, I, S> for LoggerEventManager<E, I, S, ST>
+impl<I, S, ST> EventManager<I, S> for LoggerEventManager<I, S, ST>
 where
     I: Input,
     ST: Stats, //CE: CustomEvent<I, OT>,
 {
-    fn process(&mut self, state: &mut S, _executor: &mut E) -> Result<usize, Error> {
+    fn process<E, OT>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
+    where
+        E: Executor<I> + HasObservers<OT>,
+        OT: ObserversTuple,
+    {
         let count = self.events.len();
         while self.events.len() > 0 {
             let event = self.events.pop().unwrap();
@@ -47,7 +53,7 @@ where
     }
 }
 
-impl<E, I, S, ST> LoggerEventManager<E, I, S, ST>
+impl<I, S, ST> LoggerEventManager<I, S, ST>
 where
     I: Input,
     ST: Stats, //TODO CE: CustomEvent,
diff --git a/libafl/src/events/mod.rs b/libafl/src/events/mod.rs
index a1c03ff11f..40e0fe05c6 100644
--- a/libafl/src/events/mod.rs
+++ b/libafl/src/events/mod.rs
@@ -9,7 +9,10 @@ use core::{fmt, marker::PhantomData, time::Duration};
 use serde::{Deserialize, Serialize};
 
 use crate::{
-    executors::Executor, inputs::Input, observers::ObserversTuple, state::IfInteresting, Error,
+    executors::{Executor, HasObservers},
+    inputs::Input,
+    observers::ObserversTuple,
+    Error,
 };
 
 /// The log event severity
@@ -146,7 +149,7 @@ where
 
 /// EventManager is the main communications hub.
 /// For the "normal" multi-processed mode, you may want to look into `RestartingEventManager`
-pub trait EventManager<E, I, S>
+pub trait EventManager<I, S>
 where
     I: Input,
 {
@@ -155,7 +158,10 @@ where
 
     /// Lookup for incoming events and process them.
     /// Return the number of processes events or an error
-    fn process(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>;
+    fn process<E, OT>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
+    where
+        E: Executor<I> + HasObservers<OT>,
+        OT: ObserversTuple;
 
     /// Serialize all observers for this type and manager
     fn serialize_observers<OT>(&mut self, observers: &OT) -> Result<Vec<u8>, Error>
@@ -189,16 +195,17 @@ where
 
 /// An eventmgr for tests, and as placeholder if you really don't need an event manager.
 #[derive(Copy, Clone, Debug)]
-pub struct NopEventManager<E, I, S> {
-    phantom: PhantomData<(E, I, S)>,
+pub struct NopEventManager<I, S> {
+    phantom: PhantomData<(I, S)>,
 }
-impl<E, I, S> EventManager<E, I, S> for NopEventManager<E, I, S>
+impl<I, S> EventManager<I, S> for NopEventManager<I, S>
 where
     I: Input,
 {
-    fn process(&mut self, _state: &mut S, _executor: &mut E) -> Result<usize, Error>
+    fn process<E, OT>(&mut self, state: &mut S, executor: &mut E) -> Result<usize, Error>
     where
-        E: Executor<I>,
+        E: Executor<I> + HasObservers<OT>,
+        OT: ObserversTuple,
     {
         Ok(0)
     }
diff --git a/libafl/src/executors/inprocess.rs b/libafl/src/executors/inprocess.rs
index 76a1d72a9b..36972050c5 100644
--- a/libafl/src/executors/inprocess.rs
+++ b/libafl/src/executors/inprocess.rs
@@ -56,7 +56,7 @@ where
     #[inline]
     fn pre_exec<EM, S>(&mut self, state: &mut S, event_mgr: &mut EM, input: &I) -> Result<(), Error>
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
     {
         #[cfg(unix)]
         #[cfg(feature = "std")]
@@ -69,7 +69,7 @@ where
     #[inline]
     fn post_exec<EM, S>(&mut self, _state: &S, _event_mgr: &mut EM, _input: &I) -> Result<(), Error>
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
     {
         #[cfg(unix)]
         #[cfg(feature = "std")]
@@ -132,7 +132,7 @@ where
         _event_mgr: &mut EM,
     ) -> Self
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
         OC: Corpus<I>,
         OFT: FeedbacksTuple<I>,
         S: HasObjectives<OFT, I> + HasSolutions<OC, I>,
@@ -200,7 +200,7 @@ pub mod unix_signals {
         info: siginfo_t,
         _void: c_void,
     ) where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
         OT: ObserversTuple,
         OC: Corpus<I>,
         OFT: FeedbacksTuple<I>,
@@ -273,7 +273,7 @@ pub mod unix_signals {
         info: siginfo_t,
         _void: c_void,
     ) where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
         OT: ObserversTuple,
         OC: Corpus<I>,
         OFT: FeedbacksTuple<I>,
@@ -346,7 +346,7 @@ pub mod unix_signals {
 
     pub unsafe fn setup_crash_handlers<EM, I, OC, OFT, OT, R, S>()
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
         OT: ObserversTuple,
         OC: Corpus<I>,
         OFT: FeedbacksTuple<I>,
diff --git a/libafl/src/executors/mod.rs b/libafl/src/executors/mod.rs
index 7a4a794e0d..dfe2740203 100644
--- a/libafl/src/executors/mod.rs
+++ b/libafl/src/executors/mod.rs
@@ -87,21 +87,16 @@ where
         _input: &I,
     ) -> Result<(), Error>
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
     {
         Ok(())
     }
 
     #[inline]
     /// Called right after execution finished.
-    fn post_exec<EM, S>(
-        &mut self,
-        _state: &S,
-        _event_mgr: &mut EM,
-        _input: &I,
-    ) -> Result<(), Error>
+    fn post_exec<EM, S>(&mut self, _state: &S, _event_mgr: &mut EM, _input: &I) -> Result<(), Error>
     where
-        EM: EventManager<I>,
+        EM: EventManager<I, S>,
     {
         Ok(())
     }
diff --git a/libafl/src/fuzzer.rs b/libafl/src/fuzzer.rs
index 88f5960c94..37c986a26c 100644
--- a/libafl/src/fuzzer.rs
+++ b/libafl/src/fuzzer.rs
@@ -1,20 +1,20 @@
 use crate::{
-    corpus::{Corpus, CorpusScheduler},
+    corpus::CorpusScheduler,
     events::{Event, EventManager},
-    executors::Executor,
+    executors::{Executor, HasObservers},
     inputs::Input,
+    observers::ObserversTuple,
     stages::StagesTuple,
-    state::{HasCorpus, HasExecutions, HasRand},
-    utils::{current_milliseconds, current_time, Rand},
+    state::HasExecutions,
+    utils::{current_milliseconds, current_time},
     Error,
 };
 use core::marker::PhantomData;
 
 /// Holds a set of stages
-pub trait HasStages<ST, I>
+pub trait HasStages<ST, E, EM, S>: Sized
 where
-    ST: StagesTuple<I>,
-    I: Input,
+    ST: StagesTuple<E, EM, Self, S>,
 {
     fn stages(&self) -> &ST;
 
@@ -22,9 +22,10 @@ where
 }
 
 /// Holds a scheduler
-pub trait HasCorpusScheduler<CS>
+pub trait HasCorpusScheduler<CS, I, S>
 where
-    CS: CorpusScheduler,
+    CS: CorpusScheduler<I, S>,
+    I: Input,
 {
     fn scheduler(&self) -> &CS;
 
@@ -32,50 +33,29 @@ where
 }
 
 /// The main fuzzer trait.
-pub trait Fuzzer<CS, ST, I>: HasCorpusScheduler<CS> + HasStages<ST, I>
-where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
-    I: Input,
-{
-    fn fuzz_one<E, EM, S>(
-        &self,
-        state: &mut S,
-        executor: &mut E,
-        manager: &mut EM,
-    ) -> Result<usize, Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>;
+pub trait Fuzzer<E, EM, S> {
+    fn fuzz_one(&self, state: &mut S, executor: &mut E, manager: &mut EM) -> Result<usize, Error>;
 
-    fn fuzz_loop<E, EM, S>(
-        &self,
-        state: &mut S,
-        executor: &mut E,
-        manager: &mut EM,
-    ) -> Result<usize, Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>;
+    fn fuzz_loop(&self, state: &mut S, executor: &mut E, manager: &mut EM) -> Result<usize, Error>;
 }
 
 /// Your default fuzzer instance, for everyday use.
 #[derive(Clone, Debug)]
-pub struct StdFuzzer<CS, ST, I>
+pub struct StdFuzzer<CS, ST, E, EM, I, OT, S>
 where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
+    CS: CorpusScheduler<I, S>,
+    ST: StagesTuple<E, EM, Self, S>,
     I: Input,
 {
     scheduler: CS,
     stages: ST,
-    phantom: PhantomData<I>,
+    phantom: PhantomData<(E, EM, I, OT, S)>,
 }
 
-impl<CS, ST, I> HasStages<ST, I> for StdFuzzer<CS, ST, I>
+impl<CS, ST, E, EM, I, OT, S> HasStages<ST, E, EM, S> for StdFuzzer<CS, ST, E, EM, I, OT, S>
 where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
+    CS: CorpusScheduler<I, S>,
+    ST: StagesTuple<E, EM, Self, S>,
     I: Input,
 {
     fn stages(&self) -> &ST {
@@ -87,10 +67,10 @@ where
     }
 }
 
-impl<CS, ST, I> HasCorpusScheduler<CS> for StdFuzzer<CS, ST, I>
+impl<CS, ST, E, EM, I, OT, S> HasCorpusScheduler<CS, I, S> for StdFuzzer<CS, ST, E, EM, I, OT, S>
 where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
+    CS: CorpusScheduler<I, S>,
+    ST: StagesTuple<E, EM, Self, S>,
     I: Input,
 {
     fn scheduler(&self) -> &CS {
@@ -102,25 +82,17 @@ where
     }
 }
 
-impl<CS, ST, I> Fuzzer<CS, ST, I> for StdFuzzer<CS, ST, I>
+impl<CS, ST, E, EM, I, OT, S> Fuzzer<E, EM, S> for StdFuzzer<CS, ST, E, EM, I, OT, S>
 where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
+    CS: CorpusScheduler<I, S>,
+    S: HasExecutions,
+    ST: StagesTuple<E, EM, Self, S>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
     I: Input,
 {
-    fn fuzz_one<C, E, EM, R, S>(
-        &self,
-        state: &mut S,
-        executor: &mut E,
-        manager: &mut EM,
-    ) -> Result<usize, Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>,
-        S: HasCorpus<C, I> + HasRand<R>,
-        C: Corpus<I>,
-        R: Rand,
-    {
+    fn fuzz_one(&self, state: &mut S, executor: &mut E, manager: &mut EM) -> Result<usize, Error> {
         let idx = self.scheduler().next(state)?;
 
         self.stages()
@@ -130,19 +102,7 @@ where
         Ok(idx)
     }
 
-    fn fuzz_loop<C, E, EM, R, S>(
-        &self,
-        state: &mut S,
-        executor: &mut E,
-        manager: &mut EM,
-    ) -> Result<usize, Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>,
-        S: HasCorpus<C, I> + HasRand<R> + HasExecutions,
-        C: Corpus<I>,
-        R: Rand,
-    {
+    fn fuzz_loop(&self, state: &mut S, executor: &mut E, manager: &mut EM) -> Result<usize, Error> {
         let mut last = current_milliseconds();
         loop {
             self.fuzz_one(state, executor, manager)?;
@@ -162,10 +122,10 @@ where
     }
 }
 
-impl<CS, ST, I> StdFuzzer<CS, ST, I>
+impl<CS, ST, E, EM, I, OT, S> StdFuzzer<CS, ST, E, EM, I, OT, S>
 where
-    CS: CorpusScheduler,
-    ST: StagesTuple<I>,
+    CS: CorpusScheduler<I, S>,
+    ST: StagesTuple<E, EM, Self, S>,
     I: Input,
 {
     pub fn new(scheduler: CS, stages: ST) -> Self {
diff --git a/libafl/src/inputs/bytes.rs b/libafl/src/inputs/bytes.rs
index b622a002f7..1cca7ee368 100644
--- a/libafl/src/inputs/bytes.rs
+++ b/libafl/src/inputs/bytes.rs
@@ -5,7 +5,7 @@ use alloc::{borrow::ToOwned, rc::Rc, vec::Vec};
 use core::{cell::RefCell, convert::From};
 use serde::{Deserialize, Serialize};
 
-use crate::inputs::{HasBytesVec, HasTargetBytes, HasLen, Input, TargetBytes};
+use crate::inputs::{HasBytesVec, HasLen, HasTargetBytes, Input, TargetBytes};
 
 /// A bytes input is the basic input
 #[derive(Serialize, Deserialize, Clone, Debug, Default, PartialEq, Eq)]
diff --git a/libafl/src/inputs/mod.rs b/libafl/src/inputs/mod.rs
index 09a62f698a..18b9b6a518 100644
--- a/libafl/src/inputs/mod.rs
+++ b/libafl/src/inputs/mod.rs
@@ -106,4 +106,3 @@ pub trait HasLen {
     /// The lenght
     fn len(&self) -> usize;
 }
-
diff --git a/libafl/src/lib.rs b/libafl/src/lib.rs
index 0101e09da1..c8f30e87d3 100644
--- a/libafl/src/lib.rs
+++ b/libafl/src/lib.rs
@@ -29,7 +29,7 @@ pub mod fuzzer;
 pub use fuzzer::*;
 
 use alloc::string::String;
-use core::{fmt};
+use core::fmt;
 
 #[cfg(feature = "std")]
 use std::{env::VarError, io, num::ParseIntError, string::FromUtf8Error};
@@ -199,4 +199,4 @@ mod tests {
         assert_eq!(state.corpus().count(), corpus_deserialized.count());
     }
 }
-*/
\ No newline at end of file
+*/
diff --git a/libafl/src/mutators/mod.rs b/libafl/src/mutators/mod.rs
index 3bbd89d98b..73c5203663 100644
--- a/libafl/src/mutators/mod.rs
+++ b/libafl/src/mutators/mod.rs
@@ -7,32 +7,24 @@ pub use mutations::*;
 pub mod token_mutations;
 pub use token_mutations::*;
 
-use crate::{
-    inputs::Input,
-    Error,
-};
+use crate::{inputs::Input, Error};
 
 // TODO mutator stats method that produces something that can be sent with the NewTestcase event
 // We can use it to report which mutations generated the testcase in the broker logs
 
 /// A mutator takes input, and mutates it.
 /// Simple as that.
-pub trait Mutator<I>
+pub trait Mutator<F, I, S>
 where
     I: Input,
 {
     /// Mutate a given input
-    fn mutate<F, S>(
-        &mut self,
-        fuzzer: &F,
-        state: &mut S,
-        input: &mut I,
-        stage_idx: i32,
-    ) -> Result<(), Error>;
+    fn mutate(&self, fuzzer: &F, state: &mut S, input: &mut I, stage_idx: i32)
+        -> Result<(), Error>;
 
     /// Post-process given the outcome of the execution
-    fn post_exec<F, S>(
-        &mut self,
+    fn post_exec(
+        &self,
         _fuzzer: &F,
         _state: &mut S,
         _is_interesting: u32,
diff --git a/libafl/src/mutators/mutations.rs b/libafl/src/mutators/mutations.rs
index 2813a1ebc8..c2af06a1c2 100644
--- a/libafl/src/mutators/mutations.rs
+++ b/libafl/src/mutators/mutations.rs
@@ -27,8 +27,7 @@ pub enum MutationResult {
 
 // TODO maybe the mutator arg is not needed
 /// The generic function type that identifies mutations
-pub type MutationFunction<F, I, M, S> =
-    fn(&mut M, &F, &mut S, &mut I) -> Result<MutationResult, Error>;
+pub type MutationFunction<F, I, M, S> = fn(&M, &F, &mut S, &mut I) -> Result<MutationResult, Error>;
 
 pub trait ComposedByMutations<F, I, S>
 where
@@ -125,7 +124,7 @@ const INTERESTING_32: [i32; 27] = [
 
 /// Bitflip mutation for inputs with a bytes vector
 pub fn mutation_bitflip<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -148,7 +147,7 @@ where
 }
 
 pub fn mutation_byteflip<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -171,7 +170,7 @@ where
 }
 
 pub fn mutation_byteinc<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -195,7 +194,7 @@ where
 }
 
 pub fn mutation_bytedec<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -219,7 +218,7 @@ where
 }
 
 pub fn mutation_byteneg<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -242,7 +241,7 @@ where
 }
 
 pub fn mutation_byterand<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -265,7 +264,7 @@ where
 }
 
 pub fn mutation_byteadd<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -293,7 +292,7 @@ where
 }
 
 pub fn mutation_wordadd<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -323,7 +322,7 @@ where
 }
 
 pub fn mutation_dwordadd<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -353,7 +352,7 @@ where
 }
 
 pub fn mutation_qwordadd<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -383,7 +382,7 @@ where
 }
 
 pub fn mutation_byteinteresting<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -407,7 +406,7 @@ where
 }
 
 pub fn mutation_wordinteresting<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -437,7 +436,7 @@ where
 }
 
 pub fn mutation_dwordinteresting<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -467,7 +466,7 @@ where
 }
 
 pub fn mutation_bytesdelete<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -490,7 +489,7 @@ where
 }
 
 pub fn mutation_bytesexpand<F, I, M, R, S>(
-    mutator: &mut M,
+    mutator: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -520,7 +519,7 @@ where
 }
 
 pub fn mutation_bytesinsert<F, I, M, R, S>(
-    mutator: &mut M,
+    mutator: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -553,7 +552,7 @@ where
 }
 
 pub fn mutation_bytesrandinsert<F, I, M, R, S>(
-    mutator: &mut M,
+    mutator: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -586,7 +585,7 @@ where
 }
 
 pub fn mutation_bytesset<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -611,7 +610,7 @@ where
 }
 
 pub fn mutation_bytesrandset<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -636,7 +635,7 @@ where
 }
 
 pub fn mutation_bytescopy<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -661,7 +660,7 @@ where
 }
 
 pub fn mutation_bytesswap<F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -689,7 +688,7 @@ where
 
 /// Crossover insert mutation
 pub fn mutation_crossover_insert<C, F, I, M, R, S>(
-    mutator: &mut M,
+    mutator: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -704,10 +703,13 @@ where
     let size = input.bytes().len();
 
     // We don't want to use the testcase we're already using for splicing
-    let (other_testcase, idx) = state.random_corpus_entry()?;
-    if idx == state.corpus().current_testcase().1 {
-        return Ok(MutationResult::Skipped);
+    let idx = state.rand_mut().below(state.corpus().count() as u64) as usize;
+    if let Some(cur) = state.corpus().current() {
+        if idx == *cur {
+            return Ok(MutationResult::Skipped);
+        }
     }
+    let other_testcase = state.corpus().get(idx)?;
 
     let mut other_ref = other_testcase.borrow_mut();
     let other = other_ref.load_input()?;
@@ -738,7 +740,7 @@ where
 
 /// Crossover replace mutation
 pub fn mutation_crossover_replace<C, F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -752,10 +754,13 @@ where
     let size = input.bytes().len();
 
     // We don't want to use the testcase we're already using for splicing
-    let (other_testcase, idx) = state.random_corpus_entry()?;
-    if idx == state.corpus().current_testcase().1 {
-        return Ok(MutationResult::Skipped);
+    let idx = state.rand_mut().below(state.corpus().count() as u64) as usize;
+    if let Some(cur) = state.corpus().current() {
+        if idx == *cur {
+            return Ok(MutationResult::Skipped);
+        }
     }
+    let other_testcase = state.corpus().get(idx)?;
 
     let mut other_ref = other_testcase.borrow_mut();
     let other = other_ref.load_input()?;
@@ -792,7 +797,7 @@ fn locate_diffs(this: &[u8], other: &[u8]) -> (i64, i64) {
 
 /// Splicing mutation from AFL
 pub fn mutation_splice<C, F, I, M, R, S>(
-    _: &mut M,
+    _: &M,
     fuzzer: &F,
     state: &mut S,
     input: &mut I,
@@ -804,10 +809,13 @@ where
     S: HasRand<R> + HasCorpus<C, I>,
 {
     // We don't want to use the testcase we're already using for splicing
-    let (other_testcase, idx) = state.random_corpus_entry()?;
-    if idx == state.corpus().current_testcase().1 {
-        return Ok(MutationResult::Skipped);
+    let idx = state.rand_mut().below(state.corpus().count() as u64) as usize;
+    if let Some(cur) = state.corpus().current() {
+        if idx == *cur {
+            return Ok(MutationResult::Skipped);
+        }
     }
+    let other_testcase = state.corpus().get(idx)?;
 
     let mut other_ref = other_testcase.borrow_mut();
     let other = other_ref.load_input()?;
diff --git a/libafl/src/mutators/scheduled.rs b/libafl/src/mutators/scheduled.rs
index a40e84329e..e8b880e3d9 100644
--- a/libafl/src/mutators/scheduled.rs
+++ b/libafl/src/mutators/scheduled.rs
@@ -15,27 +15,20 @@ use crate::{
 pub use crate::mutators::mutations::*;
 pub use crate::mutators::token_mutations::*;
 
-pub trait ScheduledMutator<F, I, S>: Mutator<I> + ComposedByMutations<F, I, S>
+pub trait ScheduledMutator<F, I, S>: Mutator<F, I, S> + ComposedByMutations<F, I, S>
 where
     I: Input,
 {
     /// Compute the number of iterations used to apply stacked mutations
-    fn iterations(&mut self, state: &mut S, input: &I) -> u64;
-    //{
-    //    1 << (1 + state.rand_mut().below(6))
-    //}
+    fn iterations(&self, state: &mut S, input: &I) -> u64;
 
     /// Get the next mutation to apply
-    fn schedule(&mut self, mutations_count: usize, state: &mut S, input: &I) -> usize;
-    //{
-    //    debug_assert!(mutations_count > 0);
-    //    rand.below(mutations_count as u64) as usize
-    //}
+    fn schedule(&self, mutations_count: usize, state: &mut S, input: &I) -> usize;
 
     /// New default implementation for mutate
     /// Implementations must forward mutate() to this method
     fn scheduled_mutate(
-        &mut self,
+        &self,
         fuzzer: &F,
         state: &mut S,
         input: &mut I,
@@ -50,18 +43,22 @@ where
     }
 }
 
-#[derive(Clone)]
-pub struct StdScheduledMutator<F, I, S>
+pub struct StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     mutations: Vec<MutationFunction<F, I, Self, S>>,
     max_size: usize,
+    phantom: PhantomData<R>,
 }
 
-impl<F, I, S> Debug for StdScheduledMutator<F, I, S>
+impl<F, I, R, S> Debug for StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
@@ -74,12 +71,14 @@ where
     }
 }
 
-impl<F, I, S> Mutator<I> for StdScheduledMutator<F, I, S>
+impl<F, I, R, S> Mutator<F, I, S> for StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     fn mutate(
-        &mut self,
+        &self,
         fuzzer: &F,
         state: &mut S,
         input: &mut I,
@@ -89,9 +88,11 @@ where
     }
 }
 
-impl<F, I, S> ComposedByMutations<F, I, S> for StdScheduledMutator<F, I, S>
+impl<F, I, R, S> ComposedByMutations<F, I, S> for StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     #[inline]
     fn mutation_by_idx(&self, index: usize) -> MutationFunction<F, I, Self, S> {
@@ -109,16 +110,29 @@ where
     }
 }
 
-impl<F, I, S> ScheduledMutator<F, I, S> for StdScheduledMutator<F, I, S>
+impl<F, I, R, S> ScheduledMutator<F, I, S> for StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
-    // Just use the default methods
+    /// Compute the number of iterations used to apply stacked mutations
+    fn iterations(&self, state: &mut S, input: &I) -> u64 {
+        1 << (1 + state.rand_mut().below(6))
+    }
+
+    /// Get the next mutation to apply
+    fn schedule(&self, mutations_count: usize, state: &mut S, input: &I) -> usize {
+        debug_assert!(mutations_count > 0);
+        state.rand_mut().below(mutations_count as u64) as usize
+    }
 }
 
-impl<F, I, S> HasMaxSize for StdScheduledMutator<F, I, S>
+impl<F, I, R, S> HasMaxSize for StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     #[inline]
     fn max_size(&self) -> usize {
@@ -131,15 +145,18 @@ where
     }
 }
 
-impl<F, I, S> StdScheduledMutator<F, I, S>
+impl<F, I, R, S> StdScheduledMutator<F, I, R, S>
 where
     I: Input,
+    S: HasRand<R>,
+    R: Rand,
 {
     /// Create a new StdScheduledMutator instance without mutations and corpus
     pub fn new() -> Self {
         Self {
             mutations: vec![],
             max_size: DEFAULT_MAX_SIZE,
+            phantom: PhantomData,
         }
     }
 
@@ -148,6 +165,7 @@ where
         StdScheduledMutator {
             mutations: mutations,
             max_size: DEFAULT_MAX_SIZE,
+            phantom: PhantomData,
         }
     }
 }
@@ -166,7 +184,7 @@ where
     phantom: PhantomData<(C, F, I, R, S)>,
 }
 
-impl<C, F, I, R, S, SM> Mutator<I> for HavocBytesMutator<C, F, I, R, S, SM>
+impl<C, F, I, R, S, SM> Mutator<F, I, S> for HavocBytesMutator<C, F, I, R, S, SM>
 where
     SM: ScheduledMutator<F, I, S> + HasMaxSize,
     I: Input + HasBytesVec,
@@ -176,8 +194,8 @@ where
 {
     /// Mutate bytes
     fn mutate(
-        &mut self,
-        fuzzer: &mut F,
+        &self,
+        fuzzer: &F,
         state: &mut S,
         input: &mut I,
         stage_idx: i32,
@@ -246,7 +264,7 @@ where
     }
 }
 
-impl<C, F, I, R, S> Default for HavocBytesMutator<C, F, I, R, S, StdScheduledMutator<F, I, S>>
+impl<C, F, I, R, S> Default for HavocBytesMutator<C, F, I, R, S, StdScheduledMutator<F, I, R, S>>
 where
     I: Input + HasBytesVec,
     S: HasRand<R> + HasCorpus<C, I> + HasMetadata,
@@ -255,7 +273,7 @@ where
 {
     /// Create a new HavocBytesMutator instance wrapping StdScheduledMutator
     fn default() -> Self {
-        let mut scheduled = StdScheduledMutator::<F, I, S>::new();
+        let mut scheduled = StdScheduledMutator::<F, I, R, S>::new();
         scheduled.add_mutation(mutation_bitflip);
         scheduled.add_mutation(mutation_byteflip);
         scheduled.add_mutation(mutation_byteinc);
@@ -283,8 +301,8 @@ where
         scheduled.add_mutation(mutation_bytescopy);
         scheduled.add_mutation(mutation_bytesswap);
 
-        scheduled.add_mutation(mutation_tokeninsert);
-        scheduled.add_mutation(mutation_tokenreplace);
+        //scheduled.add_mutation(mutation_tokeninsert);
+        //scheduled.add_mutation(mutation_tokenreplace);
 
         scheduled.add_mutation(mutation_crossover_insert);
         scheduled.add_mutation(mutation_crossover_replace);
diff --git a/libafl/src/mutators/token_mutations.rs b/libafl/src/mutators/token_mutations.rs
index 71635a33bd..b86937b45f 100644
--- a/libafl/src/mutators/token_mutations.rs
+++ b/libafl/src/mutators/token_mutations.rs
@@ -3,8 +3,8 @@
 
 use crate::{
     inputs::{HasBytesVec, Input},
-    state::{HasRand, HasMetadata},
     mutators::*,
+    state::{HasMetadata, HasRand},
     utils::Rand,
     Error,
 };
diff --git a/libafl/src/stages/mod.rs b/libafl/src/stages/mod.rs
index 35db374be4..45c4db9b8d 100644
--- a/libafl/src/stages/mod.rs
+++ b/libafl/src/stages/mod.rs
@@ -1,10 +1,7 @@
 pub mod mutational;
 pub use mutational::StdMutationalStage;
 
-use crate::{
-    bolts::tuples::TupleList, corpus::Corpus, events::EventManager, executors::Executor,
-    inputs::Input, Error,
-};
+use crate::{bolts::tuples::TupleList, corpus::Corpus, Error};
 
 /// A stage is one step in the fuzzing process.
 /// Multiple stages will be scheduled one by one for each input.
diff --git a/libafl/src/stages/mutational.rs b/libafl/src/stages/mutational.rs
index 89e08e8a9d..add170ba89 100644
--- a/libafl/src/stages/mutational.rs
+++ b/libafl/src/stages/mutational.rs
@@ -1,14 +1,14 @@
 use core::marker::PhantomData;
 
 use crate::{
+    corpus::Corpus,
     events::EventManager,
-    executors::Executor,
+    executors::{Executor, HasObservers},
     inputs::Input,
     mutators::Mutator,
-    stages::Corpus,
+    observers::ObserversTuple,
     stages::Stage,
-    state::HasRand,
-    state::{Evaluator, HasCorpus},
+    state::{Evaluator, HasCorpus, HasRand},
     utils::Rand,
     Error,
 };
@@ -18,10 +18,15 @@ use crate::{
 /// A Mutational stage is the stage in a fuzzing run that mutates inputs.
 /// Mutational stages will usually have a range of mutations that are
 /// being applied to the input one by one, between executions.
-pub trait MutationalStage<I, M>: Stage<I>
+pub trait MutationalStage<C, E, EM, F, I, M, OT, S>: Stage<E, EM, F, S>
 where
-    M: Mutator<I>,
+    M: Mutator<F, I, S>,
     I: Input,
+    S: HasCorpus<C, I> + Evaluator<I>,
+    C: Corpus<I>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
 {
     /// The mutator registered for this stage
     fn mutator(&self) -> &M;
@@ -30,23 +35,17 @@ where
     fn mutator_mut(&mut self) -> &mut M;
 
     /// Gets the number of iterations this mutator should run for.
-    fn iterations<S>(&mut self, state: &mut S) -> usize;
+    fn iterations(&mut self, state: &mut S) -> usize;
 
     /// Runs this (mutational) stage for the given testcase
-    fn perform_mutational<C, E, EM, F, S>(
+    fn perform_mutational(
         &self,
         fuzzer: &F,
         state: &mut S,
         executor: &mut E,
         manager: &mut EM,
         corpus_idx: usize,
-    ) -> Result<(), Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>,
-        S: HasCorpus<C, I> + Evaluator<I>,
-        C: Corpus<I>,
-    {
+    ) -> Result<(), Error> {
         let num = self.iterations(state);
         for i in 0..num {
             let mut input_mut = state
@@ -71,19 +70,32 @@ pub static DEFAULT_MUTATIONAL_MAX_ITERATIONS: u64 = 128;
 
 /// The default mutational stage
 #[derive(Clone, Debug)]
-pub struct StdMutationalStage<I, M>
+pub struct StdMutationalStage<C, E, EM, F, I, M, OT, R, S>
 where
-    M: Mutator<I>,
+    M: Mutator<F, I, S>,
     I: Input,
+    S: HasCorpus<C, I> + Evaluator<I> + HasRand<R>,
+    C: Corpus<I>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
+    R: Rand,
 {
     mutator: M,
-    phantom: PhantomData<I>,
+    phantom: PhantomData<(C, E, EM, F, I, OT, R, S)>,
 }
 
-impl<I, M> MutationalStage<I, M> for StdMutationalStage<I, M>
+impl<C, E, EM, F, I, M, OT, R, S> MutationalStage<C, E, EM, F, I, M, OT, S>
+    for StdMutationalStage<C, E, EM, F, I, M, OT, R, S>
 where
-    M: Mutator<I>,
+    M: Mutator<F, I, S>,
     I: Input,
+    S: HasCorpus<C, I> + Evaluator<I> + HasRand<R>,
+    C: Corpus<I>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
+    R: Rand,
 {
     /// The mutator, added to this stage
     #[inline]
@@ -98,43 +110,46 @@ where
     }
 
     /// Gets the number of iterations as a random number
-    fn iterations<R, S>(&mut self, state: &mut S) -> usize
-    where
-        S: HasRand<R>,
-        R: Rand,
-    {
+    fn iterations(&mut self, state: &mut S) -> usize {
         1 + state.rand_mut().below(DEFAULT_MUTATIONAL_MAX_ITERATIONS) as usize
     }
 }
 
-impl<I, M> Stage<I> for StdMutationalStage<I, M>
+impl<C, E, EM, F, I, M, OT, R, S> Stage<E, EM, F, S>
+    for StdMutationalStage<C, E, EM, F, I, M, OT, R, S>
 where
-    M: Mutator<I>,
+    M: Mutator<F, I, S>,
     I: Input,
+    S: HasCorpus<C, I> + Evaluator<I> + HasRand<R>,
+    C: Corpus<I>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
+    R: Rand,
 {
     #[inline]
-    fn perform<C, E, EM, F, S>(
+    fn perform(
         &self,
         fuzzer: &F,
         state: &mut S,
         executor: &mut E,
         manager: &mut EM,
         corpus_idx: usize,
-    ) -> Result<(), Error>
-    where
-        EM: EventManager<I>,
-        E: Executor<I>,
-        S: HasCorpus<C, I> + Evaluator<I>,
-        C: Corpus<I>,
-    {
+    ) -> Result<(), Error> {
         self.perform_mutational(fuzzer, state, executor, manager, corpus_idx)
     }
 }
 
-impl<I, M> StdMutationalStage<I, M>
+impl<C, E, EM, F, I, M, OT, R, S> StdMutationalStage<C, E, EM, F, I, M, OT, R, S>
 where
-    M: Mutator<I>,
+    M: Mutator<F, I, S>,
     I: Input,
+    S: HasCorpus<C, I> + Evaluator<I> + HasRand<R>,
+    C: Corpus<I>,
+    EM: EventManager<I, S>,
+    E: Executor<I> + HasObservers<OT>,
+    OT: ObserversTuple,
+    R: Rand,
 {
     /// Creates a new default mutational stage
     pub fn new(mutator: M) -> Self {
diff --git a/libafl/src/state/mod.rs b/libafl/src/state/mod.rs
index 0b11d67ade..eddab4e503 100644
--- a/libafl/src/state/mod.rs
+++ b/libafl/src/state/mod.rs
@@ -159,20 +159,21 @@ where
 }
 
 /// Evaluate an input modyfing the state of the fuzzer and returning a fitness
-pub trait Evaluator<I>
+pub trait Evaluator<I>: Sized
 where
     I: Input,
 {
     /// Runs the input and triggers observers and feedback
-    fn evaluate_input<E, EM>(
+    fn evaluate_input<E, EM, OT>(
         &mut self,
         input: I,
         executor: &mut E,
         event_mgr: &mut EM,
     ) -> Result<u32, Error>
     where
-        E: Executor<I>,
-        EM: EventManager<I>;
+        E: Executor<I> + HasObservers<OT>,
+        OT: ObserversTuple,
+        EM: EventManager<I, Self>;
 }
 
 /// The state a fuzz run.
@@ -442,7 +443,7 @@ where
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
         C: Corpus<I>,
-        EM: EventManager<I>,
+        EM: EventManager<I, Self>,
     {
         let (fitness, is_solution) = self.execute_input(&input, executor, manager)?;
         let observers = executor.observers();
@@ -490,7 +491,7 @@ where
         C: Corpus<BytesInput>,
         E: Executor<BytesInput> + HasObservers<OT>,
         OT: ObserversTuple,
-        EM: EventManager<BytesInput>,
+        EM: EventManager<BytesInput, Self>,
     {
         for entry in fs::read_dir(in_dir)? {
             let entry = entry?;
@@ -532,7 +533,7 @@ where
         C: Corpus<BytesInput>,
         E: Executor<BytesInput> + HasObservers<OT>,
         OT: ObserversTuple,
-        EM: EventManager<BytesInput>,
+        EM: EventManager<BytesInput, Self>,
     {
         for in_dir in in_dirs {
             self.load_from_directory(executor, manager, in_dir)?;
@@ -570,7 +571,7 @@ where
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
         C: Corpus<I>,
-        EM: EventManager<I>,
+        EM: EventManager<I, Self>,
     {
         executor.pre_exec_observers()?;
 
@@ -606,7 +607,7 @@ where
         C: Corpus<I>,
         E: Executor<I> + HasObservers<OT>,
         OT: ObserversTuple,
-        EM: EventManager<I>,
+        EM: EventManager<I, Self>,
     {
         let mut added = 0;
         for _ in 0..num {
diff --git a/libafl/src/utils.rs b/libafl/src/utils.rs
index b0eff77df9..e0dd6dd201 100644
--- a/libafl/src/utils.rs
+++ b/libafl/src/utils.rs
@@ -1,7 +1,7 @@
 //! Utility functions for AFL
 
 use core::{cell::RefCell, debug_assert, fmt::Debug, time};
-use serde::{Deserialize, Serialize, de::DeserializeOwned};
+use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use xxhash_rust::xxh3::xxh3_64_with_seed;
 
 #[cfg(feature = "std")]