diff --git a/nfuzz/libnfuzz.h b/nfuzz/libnfuzz.h
index aaf5d5876..7a8a67b87 100644
--- a/nfuzz/libnfuzz.h
+++ b/nfuzz/libnfuzz.h
@@ -12,9 +12,13 @@ extern "C" {
 void NimMain();
 
 /** Supported fuzzing tests */
+bool nfuzz_attestation(uint8_t* input_ptr, size_t input_size,
+  uint8_t* output_ptr, size_t* output_size);
+bool nfuzz_attester_slashing(uint8_t* input_ptr, size_t input_size,
+  uint8_t* output_ptr, size_t* output_size);
 bool nfuzz_block(uint8_t* input_ptr, size_t input_size,
   uint8_t* output_ptr, size_t* output_size);
-bool nfuzz_attestation(uint8_t* input_ptr, size_t input_size,
+bool nfuzz_block_header(uint8_t* input_ptr, size_t input_size,
   uint8_t* output_ptr, size_t* output_size);
 bool nfuzz_shuffle(uint8_t* seed_ptr, uint64_t* output_ptr, size_t output_size);
 
diff --git a/nfuzz/libnfuzz.nim b/nfuzz/libnfuzz.nim
index 56d61a023..58b460a10 100644
--- a/nfuzz/libnfuzz.nim
+++ b/nfuzz/libnfuzz.nim
@@ -1,7 +1,7 @@
 import
   endians, stew/ptrops, stew/ranges/ptr_arith,
   ../beacon_chain/[ssz, state_transition],
-  ../beacon_chain/spec/[datatypes, helpers, digest, validator, beaconstate],
+  ../beacon_chain/spec/[datatypes, helpers, digest, validator, beaconstate, state_transition_block],
 # Required for deserialisation of ValidatorSig in Attestation due to
 # https://github.com/nim-lang/Nim/issues/11225
   ../beacon_chain/spec/crypto
@@ -10,6 +10,10 @@ type
   BlockInput = object
     state: BeaconState
     beaconBlock: BeaconBlock
+  BlockHeaderInput = BlockInput
+  AttesterSlashingInput = object
+    state: BeaconState
+    attesterSlashing: AttesterSlashing
   AttestationInput = object
     state: BeaconState
     attestation: Attestation
@@ -43,33 +47,6 @@ proc copyState(state: BeaconState, output: ptr byte,
   copyMem(output, unsafeAddr resultState[0], output_size[])
   result = true
 
-proc nfuzz_block(input: openArray[byte], output: ptr byte,
-    output_size: ptr uint): bool {.exportc, raises:[FuzzCrashError, Defect].} =
-  var data: BlockInput
-
-  try:
-    data = SSZ.decode(input, BlockInput)
-  except MalformedSszError, SszSizeMismatchError:
-    let e = getCurrentException()
-    raise newException(FuzzCrashError, "SSZ deserialisation failed, likely bug in preprocessing.", e)
-
-  try:
-    result = state_transition(data.state, data.beaconBlock, flags = {})
-  except IOError as e:
-    # TODO why an IOError?
-    raise newException(FuzzCrashError, "Unexpected IOError in state transition", e)
-  except Exception as e:
-    # TODO why an Exception?
-    # Lots of vendor code looks like it might raise straight exceptions
-    raise newException(FuzzCrashError, "Unexpected IOError in state transition", e)
-  except ValueError:
-    # TODO is a ValueError indicative of correct or incorrect processing code?
-    # If correct (but given invalid input), we should return false
-    # If incorrect, we should allow it to crash
-    result = false
-
-  if result:
-    result = copyState(data.state, output, output_size)
 
 proc nfuzz_attestation(input: openArray[byte], output: ptr byte,
     output_size: ptr uint): bool {.exportc, raises:[FuzzCrashError, Defect].} =
@@ -95,6 +72,87 @@ proc nfuzz_attestation(input: openArray[byte], output: ptr byte,
   if result:
     result = copyState(data.state, output, output_size)
 
+
+proc nfuzz_attester_slashing(input: openArray[byte], output: ptr byte,
+    output_size: ptr uint): bool {.exportc, raises:[FuzzCrashError, Defect].} =
+  var
+    data: AttesterSlashingInput
+    cache = get_empty_per_epoch_cache()
+
+  try:
+    data = SSZ.decode(input, AttesterSlashingInput)
+  except MalformedSszError, SszSizeMismatchError:
+    let e = getCurrentException()
+    raise newException(FuzzCrashError, "SSZ deserialisation failed, likely bug in preprocessing.", e)
+
+  try:
+    result = process_attester_slashing(data.state, data.attesterSlashing, cache)
+  except ValueError:
+    # TODO is a ValueError indicative of correct or incorrect processing code?
+    # If correct (but given invalid input), we should return false
+    # If incorrect, we should allow it to crash
+    result = false
+
+  if result:
+    result = copyState(data.state, output, output_size)
+
+
+proc nfuzz_block(input: openArray[byte], output: ptr byte,
+    output_size: ptr uint): bool {.exportc, raises:[FuzzCrashError, Defect].} =
+  var data: BlockInput
+
+  try:
+    data = SSZ.decode(input, BlockInput)
+  except MalformedSszError, SszSizeMismatchError:
+    let e = getCurrentException()
+    raise newException(FuzzCrashError, "SSZ deserialisation failed, likely bug in preprocessing.", e)
+
+  try:
+    result = state_transition(data.state, data.beaconBlock, flags = {})
+  except IOError as e:
+    # TODO why an IOError?
+    raise newException(FuzzCrashError, "Unexpected IOError in state transition", e)
+  except Exception as e:
+    # TODO why an Exception?
+    # Lots of vendor code looks like it might raise a bare exception type
+    raise newException(FuzzCrashError, "Unexpected IOError in state transition", e)
+  except ValueError:
+    # TODO is a ValueError indicative of correct or incorrect processing code?
+    # If correct (but given invalid input), we should return false
+    # If incorrect, we should allow it to crash
+    result = false
+
+  if result:
+    result = copyState(data.state, output, output_size)
+
+
+proc nfuzz_block_header(input: openArray[byte], output: ptr byte,
+    output_size: ptr uint): bool {.exportc, raises:[FuzzCrashError, Defect].} =
+  var
+    data: BlockHeaderInput
+    cache = get_empty_per_epoch_cache()
+
+  try:
+    data = SSZ.decode(input, BlockHeaderInput)
+  except MalformedSszError, SszSizeMismatchError:
+    let e = getCurrentException()
+    raise newException(FuzzCrashError, "SSZ deserialisation failed, likely bug in preprocessing.", e)
+
+  try:
+    result = process_block_header(data.state, data.beaconBlock, flags = {}, cache)
+  except IOError as e:
+    # TODO why an IOError? - is this expected/should we return false?
+    raise newException(FuzzCrashError, "Unexpected IOError in block header processing", e)
+  except ValueError:
+    # TODO is a ValueError indicative of correct or incorrect processing code?
+    # If correct (but given invalid input), we should return false
+    # If incorrect, we should allow it to crash
+    result = false
+
+  if result:
+    result = copyState(data.state, output, output_size)
+
+
 # Note: Could also accept raw input pointer and access list_size + seed here.
 # However, list_size needs to be known also outside this proc to allocate output.
 # TODO: rework to copy immediatly in an uint8 openArray, considering we have to