diff --git a/src/corpus/mod.rs b/src/corpus/mod.rs
index 8d9cfc2c7b..92bcddd3b0 100644
--- a/src/corpus/mod.rs
+++ b/src/corpus/mod.rs
@@ -13,7 +13,7 @@ use crate::inputs::Input;
 use crate::utils::Rand;
 use crate::AflError;
 
-pub trait HasEntriesVec<I>
+pub trait HasTestcaseVec<I>
 where
     I: Input,
 {
@@ -25,7 +25,7 @@ where
 }
 
 /// Corpus with all current testcases
-pub trait Corpus<I, R>: HasEntriesVec<I>
+pub trait Corpus<I, R>: HasTestcaseVec<I>
 where
     I: Input,
     R: Rand,
@@ -76,6 +76,19 @@ where
     }
 }
 
+pub trait HasCorpus<C, I, R>
+where
+    C: Corpus<I, R>,
+    I: Input,
+    R: Rand,
+{
+    /// Get the corpus field
+    fn corpus(&self) -> &C;
+
+    /// Get thecorpus field (mutable)
+    fn corpus_mut(&mut self) -> &mut C;
+}
+
 pub struct InMemoryCorpus<I, R>
 where
     I: Input,
@@ -85,7 +98,7 @@ where
     phantom: PhantomData<R>,
 }
 
-impl<I, R> HasEntriesVec<I> for InMemoryCorpus<I, R>
+impl<I, R> HasTestcaseVec<I> for InMemoryCorpus<I, R>
 where
     I: Input,
     R: Rand,
@@ -131,7 +144,7 @@ where
 }
 
 #[cfg(feature = "std")]
-impl<I, R> HasEntriesVec<I> for OnDiskCorpus<I, R>
+impl<I, R> HasTestcaseVec<I> for OnDiskCorpus<I, R>
 where
     I: Input,
     R: Rand,
@@ -192,7 +205,7 @@ where
     cycles: u64,
 }
 
-impl<C, I, R> HasEntriesVec<I> for QueueCorpus<C, I, R>
+impl<C, I, R> HasTestcaseVec<I> for QueueCorpus<C, I, R>
 where
     C: Corpus<I, R>,
     I: Input,
diff --git a/src/engines/mod.rs b/src/engines/mod.rs
index e018bd9688..a861a15fb0 100644
--- a/src/engines/mod.rs
+++ b/src/engines/mod.rs
@@ -8,7 +8,7 @@ use core::fmt::Debug;
 
 use hashbrown::HashMap;
 
-use crate::corpus::{Corpus, Testcase};
+use crate::corpus::{Corpus, HasCorpus, Testcase};
 use crate::events::EventManager;
 use crate::executors::Executor;
 use crate::feedbacks::Feedback;
@@ -18,16 +18,17 @@ use crate::stages::Stage;
 use crate::utils::{HasRand, Rand};
 use crate::AflError;
 
+// TODO FeedbackMetadata to store histroy_map
+
 pub trait StateMetadata: Debug {
     /// The name of this metadata - used to find it in the list of avaliable metadatas
     fn name(&self) -> &'static str;
 }
 
-pub trait State<C, E, EM, I, R>: HasRand<R = R>
+pub trait State<C, E, I, R>: HasCorpus<C, I, R>
 where
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
@@ -37,10 +38,6 @@ where
     /// Set executions
     fn set_executions(&mut self, executions: usize);
 
-    fn events_manager(&self) -> &EM;
-
-    fn events_manager_mut(&mut self) -> &mut EM;
-
     /// Get all the metadatas into an HashMap
     fn metadatas(&self) -> &HashMap<&'static str, Box<dyn StateMetadata>>;
 
@@ -90,12 +87,6 @@ where
         self.feedbacks_mut().push(feedback);
     }
 
-    /// Return the corpus
-    fn corpus(&self) -> &C;
-
-    /// Return the corpus (mutable)
-    fn corpus_mut(&mut self) -> &mut C;
-
     /// Return the executor
     fn executor(&self) -> &E;
 
@@ -129,47 +120,43 @@ where
     }
 }
 
-pub struct DefaultState<C, E, EM, I, R>
+pub struct DefaultState<C, E, I, R>
 where
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
-    rand: R,
     executions: usize,
-    events_manager: EM,
     metadatas: HashMap<&'static str, Box<dyn StateMetadata>>,
+    // additional_corpuses: HashMap<&'static str, Box<dyn Corpus>>,
     observers: Vec<Rc<RefCell<dyn Observer>>>,
     feedbacks: Vec<Box<dyn Feedback<I>>>,
     corpus: C,
     executor: E,
 }
 
-impl<C, E, EM, I, R> HasRand for DefaultState<C, E, EM, I, R>
+impl<C, E, I, R> HasCorpus<C, I, R> for DefaultState<C, E, I, R>
 where
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
-    type R = R;
-
-    fn rand(&self) -> &Self::R {
-        &self.rand
+    fn corpus(&self) -> &C {
+        &self.corpus
     }
-    fn rand_mut(&mut self) -> &mut Self::R {
-        &mut self.rand
+
+    /// Get thecorpus field (mutable)
+    fn corpus_mut(&mut self) -> &mut C {
+        &mut self.corpus
     }
 }
 
-impl<C, E, EM, I, R> State<C, E, EM, I, R> for DefaultState<C, E, EM, I, R>
+impl<C, E, I, R> State<C, E, I, R> for DefaultState<C, E, I, R>
 where
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
@@ -181,13 +168,6 @@ where
         self.executions = executions
     }
 
-    fn events_manager(&self) -> &EM {
-        &self.events_manager
-    }
-    fn events_manager_mut(&mut self) -> &mut EM {
-        &mut self.events_manager
-    }
-
     fn metadatas(&self) -> &HashMap<&'static str, Box<dyn StateMetadata>> {
         &self.metadatas
     }
@@ -212,14 +192,6 @@ where
         &mut self.feedbacks
     }
 
-    fn corpus(&self) -> &C {
-        &self.corpus
-    }
-
-    fn corpus_mut(&mut self) -> &mut C {
-        &mut self.corpus
-    }
-
     fn executor(&self) -> &E {
         &self.executor
     }
@@ -229,19 +201,16 @@ where
     }
 }
 
-impl<C, E, EM, I, R> DefaultState<C, E, EM, I, R>
+impl<C, E, I, R> DefaultState<C, E, I, R>
 where
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
-    pub fn new(corpus: C, executor: E, events_manager: EM, rand: R) -> Self {
+    pub fn new(corpus: C, executor: E) -> Self {
         DefaultState {
-            rand: rand,
             executions: 0,
-            events_manager: events_manager,
             metadatas: HashMap::default(),
             observers: vec![],
             feedbacks: vec![],
@@ -253,23 +222,28 @@ where
 
 pub trait Engine<S, C, E, EM, I, R>
 where
-    S: State<C, E, EM, I, R>,
+    S: State<C, E, I, R>,
     C: Corpus<I, R>,
     E: Executor<I>,
     EM: EventManager,
     I: Input,
     R: Rand,
 {
-    fn stages(&self) -> &[Box<dyn Stage<S, C, E, EM, I, R>>];
+    fn stages(&self) -> &[Box<dyn Stage<S, C, E, I, R>>];
 
-    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<S, C, E, EM, I, R>>>;
+    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<S, C, E, I, R>>>;
 
-    fn add_stage(&mut self, stage: Box<dyn Stage<S, C, E, EM, I, R>>) {
+    fn add_stage(&mut self, stage: Box<dyn Stage<S, C, E, I, R>>) {
         self.stages_mut().push(stage);
     }
 
-    fn fuzz_one(&mut self, state: &mut S) -> Result<usize, AflError> {
-        let (testcase, idx) = state.corpus_mut().next(state.rand_mut())?;
+    fn fuzz_one(
+        &mut self,
+        rand: &mut R,
+        state: &mut S,
+        events_manager: &mut EM,
+    ) -> Result<usize, AflError> {
+        let (testcase, idx) = state.corpus_mut().next(rand)?;
         println!("Cur entry: {}\tExecutions: {}", idx, state.executions());
         for stage in self.stages_mut() {
             stage.perform(testcase.clone(), state)?;
@@ -287,30 +261,30 @@ where
     I: Input,
     R: Rand,
 {
-    stages: Vec<Box<dyn Stage<S, C, E, EM, I, R>>>,
+    stages: Vec<Box<dyn Stage<S, C, E, I, R>>>,
 }
 
 impl<S, C, E, EM, I, R> Engine<S, C, E, EM, I, R> for DefaultEngine<S, C, E, EM, I, R>
 where
-    S: State<C, E, EM, I, R>,
+    S: State<C, E, I, R>,
     C: Corpus<I, R>,
     E: Executor<I>,
     EM: EventManager,
     I: Input,
     R: Rand,
 {
-    fn stages(&self) -> &[Box<dyn Stage<S, C, E, EM, I, R>>] {
+    fn stages(&self) -> &[Box<dyn Stage<S, C, E, I, R>>] {
         &self.stages
     }
 
-    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<S, C, E, EM, I, R>>> {
+    fn stages_mut(&mut self) -> &mut Vec<Box<dyn Stage<S, C, E, I, R>>> {
         &mut self.stages
     }
 }
 
 impl<S, C, E, EM, I, R> DefaultEngine<S, C, E, EM, I, R>
 where
-    S: State<C, E, EM, I, R>,
+    S: State<C, E, I, R>,
     C: Corpus<I, R>,
     E: Executor<I>,
     EM: EventManager,
diff --git a/src/mutators/mod.rs b/src/mutators/mod.rs
index 0c0ecdb9ec..28ee775e27 100644
--- a/src/mutators/mod.rs
+++ b/src/mutators/mod.rs
@@ -12,7 +12,7 @@ use crate::AflError;
 
 pub trait Mutator<S, C, I, R>
 where
-    S: HasRand<R = R> + HasCorpus<C>,
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
diff --git a/src/mutators/scheduled.rs b/src/mutators/scheduled.rs
index 1c5460aa17..5046307eb0 100644
--- a/src/mutators/scheduled.rs
+++ b/src/mutators/scheduled.rs
@@ -18,7 +18,7 @@ type MutationFunction<M, S, I> = fn(&mut M, &mut S, &mut I) -> Result<MutationRe
 
 pub trait ComposedByMutations<S, C, I, R>
 where
-    S: HasRand<R = R> + HasCorpus<C>,
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
@@ -36,7 +36,7 @@ where
 pub trait ScheduledMutator<S, C, I, R>:
     Mutator<S, C, I, R> + ComposedByMutations<S, C, I, R>
 where
-    S: HasRand<R = R> + HasCorpus<C>,
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
@@ -90,23 +90,19 @@ where
 
 impl<S, C, I, R> Mutator<S, C, I, R> for DefaultScheduledMutator<S, C, I, R>
 where
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
 {
-    fn mutate(
-        &mut self,
-        corpus: &mut C,
-        rand: &mut R,
-        input: &mut I,
-        _stage_idx: i32,
-    ) -> Result<(), AflError> {
-        self.scheduled_mutate(corpus, rand, input, _stage_idx)
+    fn mutate(&mut self, state: &mut S, input: &mut I, _stage_idx: i32) -> Result<(), AflError> {
+        self.scheduled_mutate(state, input, _stage_idx)
     }
 }
 
 impl<S, C, I, R> ComposedByMutations<S, C, I, R> for DefaultScheduledMutator<S, C, I, R>
 where
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
@@ -127,8 +123,9 @@ where
     }
 }
 
-impl<C, I, R> ScheduledMutator<C, I, R> for DefaultScheduledMutator<C, I, R>
+impl<S, C, I, R> ScheduledMutator<S, C, I, R> for DefaultScheduledMutator<S, C, I, R>
 where
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
@@ -136,8 +133,9 @@ where
     // Just use the default methods
 }
 
-impl<C, I, R> DefaultScheduledMutator<C, I, R>
+impl<S, C, I, R> DefaultScheduledMutator<S, C, I, R>
 where
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input,
     R: Rand,
@@ -156,19 +154,19 @@ where
 }
 
 /// Bitflip mutation for inputs with a bytes vector
-pub fn mutation_bitflip<M, C, R, I>(
+pub fn mutation_bitflip<M, S, C, R, I>(
     mutator: &mut M,
-    _corpus: &mut C,
-    rand: &mut R,
+    state: &mut S,
     input: &mut I,
 ) -> Result<MutationResult, AflError>
 where
-    M: Mutator<C, I, R>,
+    M: Mutator<S, C, I, R>,
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input + HasBytesVec,
     R: Rand,
 {
-    let bit = rand.below((input.bytes().len() * 8) as u64) as usize;
+    let bit = state.rand_mut().below((input.bytes().len() * 8) as u64) as usize;
     input.bytes_mut()[bit >> 3] ^= (128 >> (bit & 7)) as u8;
     Ok(MutationResult::Mutated)
 }
@@ -190,14 +188,14 @@ fn locate_diffs(this: &[u8], other: &[u8]) -> (i64, i64) {
 }
 
 /// Splicing mutator
-pub fn mutation_splice<C, M, R, I>(
+pub fn mutation_splice<M, S, C, R, I>(
     mutator: &mut M,
-    corpus: &mut C,
-    rand: &mut R,
+    state: &mut S,
     input: &mut I,
 ) -> Result<MutationResult, AflError>
 where
-    M: Mutator<C, I, R>,
+    M: Mutator<S, C, I, R>,
+    S: HasRand<R> + HasCorpus<C, I, R>,
     C: Corpus<I, R>,
     I: Input + HasBytesVec,
     R: Rand,
@@ -206,7 +204,7 @@ where
     // We don't want to use the testcase we're already using for splicing
     let other_rr = loop {
         let mut found = false;
-        let (other_rr, _) = corpus.random_entry(rand)?.clone();
+        let (other_rr, _) = state.corpus_mut().random_entry(state.rand_mut())?.clone();
         match other_rr.try_borrow_mut() {
             Ok(_) => found = true,
             Err(_) => {
diff --git a/src/stages/mod.rs b/src/stages/mod.rs
index 8d06aa2fb8..b70318fb0f 100644
--- a/src/stages/mod.rs
+++ b/src/stages/mod.rs
@@ -4,7 +4,6 @@ pub use mutational::DefaultMutationalStage;
 use crate::corpus::testcase::Testcase;
 use crate::corpus::Corpus;
 use crate::engines::State;
-use crate::events::EventManager;
 use crate::executors::Executor;
 use crate::inputs::Input;
 use crate::utils::Rand;
@@ -12,19 +11,19 @@ use crate::AflError;
 use alloc::rc::Rc;
 use core::cell::RefCell;
 
-pub trait Stage<S, C, E, EM, I, R>
+pub trait Stage<S, C, E, I, R>
 where
-    S: State<C, E, EM, I, R>,
+    S: State<C, E, I, R>,
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
     /// Run the stage
     fn perform(
         &mut self,
-        testcase: Rc<RefCell<Testcase<I>>>,
+        rand: &mut R,
         state: &mut S,
+        testcase: Rc<RefCell<Testcase<I>>>,
     ) -> Result<(), AflError>;
 }
diff --git a/src/stages/mutational.rs b/src/stages/mutational.rs
index f700781396..79c1129ebe 100644
--- a/src/stages/mutational.rs
+++ b/src/stages/mutational.rs
@@ -15,13 +15,12 @@ use crate::AflError;
 
 // TODO multi mutators stage
 
-pub trait MutationalStage<M, S, C, E, EM, I, R>: Stage<S, C, E, EM, I, R>
+pub trait MutationalStage<M, S, C, E, I, R>: Stage<S, C, E, I, R>
 where
     M: Mutator<C, I, R>,
-    S: State<C, E, EM, I, R>,
+    S: State<C, E, I, R>,
     C: Corpus<I, R>,
     E: Executor<I>,
-    EM: EventManager,
     I: Input,
     R: Rand,
 {
@@ -40,15 +39,17 @@ where
     /// Runs this (mutational) stage for the given testcase
     fn perform_mutational(
         &mut self,
-        testcase: Rc<RefCell<Testcase<I>>>,
+        rand: &mut R,
         state: &mut S,
+        testcase: Rc<RefCell<Testcase<I>>>,
     ) -> Result<(), AflError> {
-        let num = self.iterations(state.rand_mut());
+        let num = self.iterations(rand);
         let input = testcase.borrow_mut().load_input()?.clone();
 
         for i in 0..num {
             let mut input_tmp = input.clone();
-            self.mutator_mut().mutate(state, &mut input_tmp, i as i32)?;
+            self.mutator_mut()
+                .mutate(rand, state, &mut input_tmp, i as i32)?;
 
             let interesting = state.evaluate_input(&input_tmp)?;
 
diff --git a/src/utils.rs b/src/utils.rs
index e7db765b8f..77261a2f25 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -47,27 +47,27 @@ pub trait Rand: Debug {
 }
 
 /// Has a Rand field, that can be used to get random values
-pub trait HasRand {
-    type R: Rand;
-
-    /// Get the hold Rand instance
-    fn rand(&self) -> &Self::R;
-
-    /// Get the hold Rand instance (mutable)
-    fn rand_mut(&mut self) -> &mut Self::R;
+pub trait HasRand<R>
+where
+    R: Rand,
+{
+    /// Get the hold RefCell Rand instance
+    fn rand(&self) -> &RefCell<R>;
 
     // Gets the next 64 bit value
     fn rand_next(&mut self) -> u64 {
-        self.rand_mut().next()
+        self.rand().borrow_mut().next()
     }
     // Gets a value below the given 64 bit val (inclusive)
     fn rand_below(&mut self, upper_bound_excl: u64) -> u64 {
-        self.rand_mut().below(upper_bound_excl)
+        self.rand().borrow_mut().below(upper_bound_excl)
     }
 
     // Gets a value between the given lower bound (inclusive) and upper bound (inclusive)
     fn rand_between(&mut self, lower_bound_incl: u64, upper_bound_incl: u64) -> u64 {
-        self.rand_mut().between(lower_bound_incl, upper_bound_incl)
+        self.rand()
+            .borrow_mut()
+            .between(lower_bound_incl, upper_bound_incl)
     }
 }