diff --git a/beacon_chain/beacon_node_types.nim b/beacon_chain/beacon_node_types.nim
index c88cef818..0c7dfd054 100644
--- a/beacon_chain/beacon_node_types.nim
+++ b/beacon_chain/beacon_node_types.nim
@@ -98,7 +98,6 @@ type
     ## Records voluntary exit indices seen.
 
     dag*: ChainDAGRef
-    quarantine*: QuarantineRef
 
   # #############################################
   #
diff --git a/beacon_chain/consensus_object_pools/blockchain_dag.nim b/beacon_chain/consensus_object_pools/blockchain_dag.nim
index f54ea5a42..5da70db1d 100644
--- a/beacon_chain/consensus_object_pools/blockchain_dag.nim
+++ b/beacon_chain/consensus_object_pools/blockchain_dag.nim
@@ -132,7 +132,7 @@ func validatorKey*(
   ## at any point in time - this function may return pubkeys for indicies that
   ## are not (yet) part of the head state (if the key has been observed on a
   ## non-head branch)!
-  epochRef.dag.validatorKey(index)
+  validatorKey(epochRef.dag, index)
 
 func init*(
     T: type EpochRef, dag: ChainDAGRef, state: StateData,
@@ -148,7 +148,9 @@ func init*(
         getStateField(state.data, current_justified_checkpoint),
       finalized_checkpoint: getStateField(state.data, finalized_checkpoint),
       shuffled_active_validator_indices:
-        cache.get_shuffled_active_validator_indices(state.data, epoch))
+        cache.get_shuffled_active_validator_indices(state.data, epoch)
+      )
+
   for i in 0'u64..<SLOTS_PER_EPOCH:
     epochRef.beacon_proposers[i] = get_beacon_proposer_index(
       state.data, cache, epoch.compute_start_slot_at_epoch() + i)
@@ -683,13 +685,11 @@ proc getForkedBlock*(dag: ChainDAGRef, blck: BlockRef): ForkedTrustedSignedBeaco
   # TODO implement this properly
   let phase0Block = dag.db.getBlock(blck.root)
   if phase0Block.isOk:
-    return ForkedTrustedSignedBeaconBlock(kind: BeaconBlockFork.Phase0,
-                                          phase0Block: phase0Block.get)
+    return ForkedTrustedSignedBeaconBlock.init(phase0Block.get)
 
   let altairBlock = dag.db.getAltairBlock(blck.root)
   if altairBlock.isOk:
-    return ForkedTrustedSignedBeaconBlock(kind: BeaconBlockFork.Altair,
-                                          altairBlock: altairBlock.get)
+    return ForkedTrustedSignedBeaconBlock.init(altairBlock.get)
 
   raiseAssert "BlockRef without backing data, database corrupt?"
 
diff --git a/beacon_chain/consensus_object_pools/exit_pool.nim b/beacon_chain/consensus_object_pools/exit_pool.nim
index 0d5d054f1..0f99b2135 100644
--- a/beacon_chain/consensus_object_pools/exit_pool.nim
+++ b/beacon_chain/consensus_object_pools/exit_pool.nim
@@ -15,10 +15,10 @@ import
   # Internal
   ../spec/[forks, helpers],
   ../spec/datatypes/base,
-  "."/[blockchain_dag, block_quarantine],
+  "."/[blockchain_dag],
   ../beacon_node_types
 
-export beacon_node_types, intsets
+export beacon_node_types, base, intsets, deques
 
 logScope: topics = "exitpool"
 
@@ -28,7 +28,7 @@ const
   VOLUNTARY_EXITS_BOUND* = MAX_VOLUNTARY_EXITS * 2
 
 proc init*(
-    T: type ExitPool, dag: ChainDAGRef, quarantine: QuarantineRef): T =
+    T: type ExitPool, dag: ChainDAGRef): T =
   ## Initialize an ExitPool from the dag `headState`
   T(
     # Allow for filtering out some exit messages during block production
@@ -39,7 +39,6 @@ proc init*(
     voluntary_exits:
       initDeque[SignedVoluntaryExit](initialSize = VOLUNTARY_EXITS_BOUND.int),
     dag: dag,
-    quarantine: quarantine
    )
 
 func addExitMessage*(subpool: var auto, exitMessage, bound: auto) =
diff --git a/beacon_chain/consensus_object_pools/spec_cache.nim b/beacon_chain/consensus_object_pools/spec_cache.nim
index 540716b75..371ea088e 100644
--- a/beacon_chain/consensus_object_pools/spec_cache.nim
+++ b/beacon_chain/consensus_object_pools/spec_cache.nim
@@ -193,3 +193,9 @@ iterator get_committee_assignments*(
           includedIndices, idx,
           compute_subnet_for_attestation(committees_per_slot, slot, idx),
           slot)
+
+func is_aggregator*(epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
+    slot_signature: ValidatorSig): bool =
+  let
+    committee_len = get_beacon_committee_len(epochRef, slot, index)
+  return is_aggregator(committee_len, slot_signature)
diff --git a/beacon_chain/gossip_processing/gossip_validation.nim b/beacon_chain/gossip_processing/gossip_validation.nim
index 399d1702e..d0315b772 100644
--- a/beacon_chain/gossip_processing/gossip_validation.nim
+++ b/beacon_chain/gossip_processing/gossip_validation.nim
@@ -9,7 +9,7 @@
 
 import
   # Standard library
-  std/[intsets, deques],
+  std/[intsets],
   # Status
   chronicles, chronos, metrics,
   stew/results,
@@ -18,11 +18,8 @@ import
   ../spec/[
     beaconstate, state_transition_block, forks, helpers, network, signatures],
   ../consensus_object_pools/[
-    spec_cache, blockchain_dag, block_quarantine, spec_cache,
-    attestation_pool, exit_pool
-  ],
+    attestation_pool, blockchain_dag, block_quarantine, exit_pool, spec_cache],
   ".."/[beacon_node_types, beacon_clock],
-  ../validators/attestation_aggregation,
   ./batch_validation
 
 from libp2p/protocols/pubsub/pubsub import ValidationResult
@@ -38,6 +35,11 @@ declareCounter beacon_attestations_dropped_queue_full,
 declareCounter beacon_aggregates_dropped_queue_full,
   "Number of aggregates dropped because queue is full"
 
+template errIgnore(msg: cstring): untyped =
+  err((ValidationResult.Ignore, cstring msg))
+template errReject(msg: cstring): untyped =
+  err((ValidationResult.Reject, cstring msg))
+
 # Internal checks
 # ----------------------------------------------------------------
 
@@ -50,20 +52,18 @@ func check_attestation_block(
   # useless - other blocks that are not rooted in the finalized chain will be
   # pruned by the chain dag, and thus we can no longer get a BlockRef for them
   if not (blck.slot > pool.dag.finalizedHead.slot):
-    return err((ValidationResult.Ignore, cstring(
-      "Voting for already-finalized block")))
+    return errIgnore("Voting for already-finalized block")
 
   # The attestation shouldn't be voting for a block that didn't exist at the
   # time - not in spec, but hard to reason about
   if not (attestationSlot >= blck.slot):
-    return err((ValidationResult.Ignore, cstring(
-      "Voting for block that didn't exist at the time")))
+    return errIgnore("Voting for block that didn't exist at the time")
 
   # We'll also cap it at 4 epochs which is somewhat arbitrary, but puts an
   # upper bound on the processing done to validate the attestation
   # TODO revisit with less arbitrary approach
   if not ((attestationSlot - blck.slot) <= uint64(4 * SLOTS_PER_EPOCH)):
-    return err((ValidationResult.Ignore, cstring("Voting for very old block")))
+    return errIgnore("Voting for very old block")
 
   ok()
 
@@ -74,8 +74,7 @@ func check_propagation_slot_range(
     futureSlot = (wallTime + MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot()
 
   if not futureSlot.afterGenesis or msgSlot > futureSlot.slot:
-    return err((ValidationResult.Ignore, cstring(
-      "Attestation slot in the future")))
+    return errIgnore("Attestation slot in the future")
 
   let
     pastSlot = (wallTime - MAXIMUM_GOSSIP_CLOCK_DISPARITY).toSlot()
@@ -88,8 +87,7 @@ func check_propagation_slot_range(
 
   if pastSlot.afterGenesis and
       msgSlot + ATTESTATION_PROPAGATION_SLOT_RANGE < pastSlot.slot:
-    return err((ValidationResult.Ignore, cstring(
-      "Attestation slot in the past")))
+    return errIgnore("Attestation slot in the past")
 
   ok()
 
@@ -104,7 +102,7 @@ func check_beacon_and_target_block(
   let blck = pool.dag.getRef(data.beacon_block_root)
   if blck.isNil:
     pool.quarantine.addMissing(data.beacon_block_root)
-    return err((ValidationResult.Ignore, cstring("Attestation block unknown")))
+    return errIgnore("Attestation block unknown")
 
   # Not in spec - check that rewinding to the state is sane
   ? check_attestation_block(pool, data.slot, blck)
@@ -119,8 +117,8 @@ func check_beacon_and_target_block(
       blck, compute_start_slot_at_epoch(data.target.epoch), SLOTS_PER_EPOCH.int)
 
   if not (target.root == data.target.root):
-    return err((ValidationResult.Reject, cstring(
-      "attestation's target block not an ancestor of LMD vote block")))
+    return errIgnore(
+      "Attestation's target block not an ancestor of LMD vote block")
 
   ok(target)
 
@@ -130,11 +128,9 @@ func check_aggregation_count(
 
   let ones = attestation.aggregation_bits.countOnes()
   if singular and ones != 1:
-    return err((ValidationResult.Reject, cstring(
-      "Attestation must have a single attestation bit set")))
+    return errReject("Attestation must have a single attestation bit set")
   elif not singular and ones < 1:
-    return err((ValidationResult.Reject, cstring(
-      "Attestation must have at least one attestation bit set")))
+    return errReject("Attestation must have at least one attestation bit set")
 
   ok()
 
@@ -148,15 +144,14 @@ func check_attestation_subnet(
         attestation.data.slot, attestation.data.index.CommitteeIndex)
 
   if expectedSubnet != subnet_id:
-    return err((ValidationResult.Reject, cstring(
-      "Attestation not on the correct subnet")))
+    return errReject("Attestation not on the correct subnet")
 
   ok()
 
 # Gossip Validation
 # ----------------------------------------------------------------
 
-template errReject(msg: cstring): untyped =
+template checkedReject(msg: cstring): untyped =
   if verifyFinalization in pool.dag.updateFlags:
     # This doesn't depend on the wall clock or the exact state of the DAG; it's
     # an internal consistency/correctness check only, and effectively never has
@@ -164,7 +159,7 @@ template errReject(msg: cstring): untyped =
     raiseAssert $msg
   err((ValidationResult.Reject, cstring msg))
 
-template errReject(error: (ValidationResult, cstring)): untyped =
+template checkedReject(error: (ValidationResult, cstring)): untyped =
   doAssert error[0] == ValidationResult.Reject
   if verifyFinalization in pool.dag.updateFlags:
     # This doesn't depend on the wall clock or the exact state of the DAG; it's
@@ -173,9 +168,6 @@ template errReject(error: (ValidationResult, cstring)): untyped =
     raiseAssert $error[1]
   err(error)
 
-template errIgnore(msg: cstring): untyped =
-  err((ValidationResult.Ignore, cstring msg))
-
 # https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/p2p-interface.md#beacon_attestation_subnet_id
 proc validateAttestation*(
     pool: ref AttestationPool,
@@ -196,7 +188,7 @@ proc validateAttestation*(
   block:
     let v = check_attestation_slot_target(attestation.data)
     if v.isErr():
-      return errReject(v.error)
+      return checkedReject(v.error)
 
   # attestation.data.slot is within the last ATTESTATION_PROPAGATION_SLOT_RANGE
   # slots (within a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance) -- i.e.
@@ -214,7 +206,7 @@ proc validateAttestation*(
   block:
     let v = check_aggregation_count(attestation, singular = true) # [REJECT]
     if v.isErr():
-      return errReject(v.error)
+      return checkedReject(v.error)
 
   # The block being voted for (attestation.data.beacon_block_root) has been seen
   # (via both gossip and non-gossip sources) (a client MAY queue attestations for
@@ -242,8 +234,7 @@ proc validateAttestation*(
   # [REJECT] The committee index is within the expected range -- i.e.
   # data.index < get_committee_count_per_slot(state, data.target.epoch).
   if not (attestation.data.index < get_committee_count_per_slot(epochRef)):
-    return errReject(cstring(
-      "validateAttestation: committee index not within expected range"))
+    return checkedReject("Attestation: committee index not within expected range")
 
   # [REJECT] The attestation is for the correct subnet -- i.e.
   # compute_subnet_for_attestation(committees_per_slot,
@@ -265,8 +256,8 @@ proc validateAttestation*(
   # attestation.data.beacon_block_root.
   if not (attestation.aggregation_bits.lenu64 == get_beacon_committee_len(
       epochRef, attestation.data.slot, attestation.data.index.CommitteeIndex)):
-    return errReject(cstring(
-      "validateAttestation: number of aggregation bits and committee size mismatch"))
+    return checkedReject(
+      "Attestation: number of aggregation bits and committee size mismatch")
 
   let
     fork = pool.dag.forkAtEpoch(attestation.data.slot.epoch)
@@ -288,8 +279,7 @@ proc validateAttestation*(
   if (pool.nextAttestationEpoch.lenu64 > validator_index.uint64) and
       pool.nextAttestationEpoch[validator_index].subnet >
         attestation.data.target.epoch:
-    return err((ValidationResult.Ignore, cstring(
-      "Validator has already voted in epoch")))
+    return errIgnore("Attestation: Validator has already voted in epoch")
 
   block:
     # First pass - without cryptography
@@ -297,7 +287,7 @@ proc validateAttestation*(
         fork, genesis_validators_root, epochRef, attestation,
         {skipBLSValidation})
     if v.isErr():
-      return errReject(v.error)
+      return checkedReject(v.error)
 
   let sig =
     if checkSignature:
@@ -308,7 +298,7 @@ proc validateAttestation*(
                               attestation
                             )
       if deferredCrypto.isErr():
-        return errReject(deferredCrypto.error)
+        return checkedReject(deferredCrypto.error)
 
       # Await the crypto check
       let
@@ -317,18 +307,16 @@ proc validateAttestation*(
       var x = (await cryptoFut)
       case x
       of BatchResult.Invalid:
-        return errReject("validateAttestation: invalid signature")
+        return checkedReject("Attestation: invalid signature")
       of BatchResult.Timeout:
         beacon_attestations_dropped_queue_full.inc()
-        return err((ValidationResult.Ignore, cstring("validateAttestation: timeout checking signature")))
+        return errIgnore("Attestation: timeout checking signature")
       of BatchResult.Valid:
         sig # keep going only in this case
     else:
       let sig = attestation.signature.load()
       if not sig.isSome():
-        return err((
-          ValidationResult.Ignore,
-          cstring("validateAttestation: unable to load signature")))
+        return checkedReject("Attestation: unable to load signature")
       sig.get()
 
   # Only valid attestations go in the list, which keeps validator_index
@@ -361,7 +349,7 @@ proc validateAggregate*(
   block:
     let v = check_attestation_slot_target(aggregate.data)
     if v.isErr():
-      return errReject(v.error)
+      return checkedReject(v.error)
 
   # [IGNORE] aggregate.data.slot is within the last
   # ATTESTATION_PROPAGATION_SLOT_RANGE slots (with a
@@ -390,7 +378,7 @@ proc validateAggregate*(
       pool.nextAttestationEpoch[
           aggregate_and_proof.aggregator_index].aggregate >
         aggregate.data.target.epoch:
-    return errIgnore("validateAggregate: Validator has already aggregated in epoch")
+    return errIgnore("Aggregate: validator has already aggregated in epoch")
 
   # [REJECT] The attestation has participants -- that is,
   # len(get_attesting_indices(state, aggregate.data, aggregate.aggregation_bits)) >= 1.
@@ -425,10 +413,15 @@ proc validateAggregate*(
   let
     epochRef = pool.dag.getEpochRef(target, aggregate.data.target.epoch)
 
+  # [REJECT] The committee index is within the expected range -- i.e.
+  # data.index < get_committee_count_per_slot(state, data.target.epoch).
+  if not (aggregate.data.index < get_committee_count_per_slot(epochRef)):
+    return checkedReject("Aggregate: committee index not within expected range")
+
   if not is_aggregator(
       epochRef, aggregate.data.slot, aggregate.data.index.CommitteeIndex,
       aggregate_and_proof.selection_proof):
-    return errReject(cstring("Incorrect aggregator"))
+    return checkedReject("Aggregate: incorrect aggregator")
 
   # [REJECT] The aggregator's validator index is within the committee -- i.e.
   # aggregate_and_proof.aggregator_index in get_beacon_committee(state,
@@ -436,8 +429,7 @@ proc validateAggregate*(
   if aggregate_and_proof.aggregator_index.ValidatorIndex notin
       get_beacon_committee(
         epochRef, aggregate.data.slot, aggregate.data.index.CommitteeIndex):
-    return errReject(cstring(
-      "Aggregator's validator index not in committee"))
+    return checkedReject("Aggregate: aggregator's validator index not in committee")
 
   # 1. [REJECT] The aggregate_and_proof.selection_proof is a valid signature of the
   #    aggregate.data.slot by the validator with index
@@ -457,7 +449,7 @@ proc validateAggregate*(
                   signed_aggregate_and_proof
                 )
   if deferredCrypto.isErr():
-    return errReject(deferredCrypto.error)
+    return checkedReject(deferredCrypto.error)
 
   let
     (cryptoFuts, sig) = deferredCrypto.get()
@@ -467,10 +459,10 @@ proc validateAggregate*(
     var x = await cryptoFuts.slotCheck
     case x
     of BatchResult.Invalid:
-      return errReject(cstring("validateAggregate: invalid slot signature"))
+      return checkedReject("Aggregate: invalid slot signature")
     of BatchResult.Timeout:
       beacon_aggregates_dropped_queue_full.inc()
-      return err((ValidationResult.Reject, cstring("validateAggregate: timeout checking slot signature")))
+      return errIgnore("Aggregate: timeout checking slot signature")
     of BatchResult.Valid:
       discard
 
@@ -479,10 +471,10 @@ proc validateAggregate*(
     var x = await cryptoFuts.aggregatorCheck
     case x
     of BatchResult.Invalid:
-      return errReject("validateAggregate: invalid aggregator signature")
+      return checkedReject("Aggregate: invalid aggregator signature")
     of BatchResult.Timeout:
       beacon_aggregates_dropped_queue_full.inc()
-      return err((ValidationResult.Reject, cstring("validateAggregate: timeout checking aggregator signature")))
+      return errIgnore("Aggregate: timeout checking aggregator signature")
     of BatchResult.Valid:
       discard
 
@@ -491,10 +483,10 @@ proc validateAggregate*(
     var x = await cryptoFuts.aggregateCheck
     case x
     of BatchResult.Invalid:
-      return errReject("validateAggregate: invalid aggregate signature")
+      return checkedReject("Aggregate: invalid aggregate signature")
     of BatchResult.Timeout:
       beacon_aggregates_dropped_queue_full.inc()
-      return err((ValidationResult.Reject, cstring("validateAggregate: timeout checking aggregate signature")))
+      return errIgnore("Aggregate: timeout checking aggregate signature")
     of BatchResult.Valid:
       discard
 
@@ -660,7 +652,6 @@ proc isValidBeaconBlock*(
 
   ok()
 
-
 # https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/p2p-interface.md#attester_slashing
 proc validateAttesterSlashing*(
     pool: var ExitPool, attester_slashing: AttesterSlashing):
@@ -681,8 +672,8 @@ proc validateAttesterSlashing*(
 
   if not disjoint(
       attester_slashed_indices, pool.prior_seen_attester_slashed_indices):
-    return err((ValidationResult.Ignore, cstring(
-      "validateAttesterSlashing: attester-slashed index already attester-slashed")))
+    return errIgnore(
+      "AttesterSlashing: attester-slashed index already attester-slashed")
 
   # [REJECT] All of the conditions within process_attester_slashing pass
   # validation.
@@ -703,16 +694,15 @@ proc validateProposerSlashing*(
     Result[bool, (ValidationResult, cstring)] =
   # Not from spec; the rest of NBC wouldn't have correctly processed it either.
   if proposer_slashing.signed_header_1.message.proposer_index > high(int).uint64:
-    return err((ValidationResult.Ignore, cstring(
-      "validateProposerSlashing: proposer-slashed index too high")))
+    return errIgnore("ProposerSlashing: proposer-slashed index too high")
 
   # [IGNORE] The proposer slashing is the first valid proposer slashing
   # received for the proposer with index
   # proposer_slashing.signed_header_1.message.proposer_index.
   if proposer_slashing.signed_header_1.message.proposer_index.int in
       pool.prior_seen_proposer_slashed_indices:
-    return err((ValidationResult.Ignore, cstring(
-      "validateProposerSlashing: proposer-slashed index already proposer-slashed")))
+    return errIgnore(
+      "ProposerSlashing: proposer-slashed index already proposer-slashed")
 
   # [REJECT] All of the conditions within process_proposer_slashing pass validation.
   let proposer_slashing_validity =
@@ -735,16 +725,14 @@ proc validateVoluntaryExit*(
   # the validator with index signed_voluntary_exit.message.validator_index.
   if signed_voluntary_exit.message.validator_index >=
       getStateField(pool.dag.headState.data, validators).lenu64:
-    return err((ValidationResult.Ignore, cstring(
-      "validateVoluntaryExit: validator index too high")))
+    return errIgnore("VoluntaryExit: validator index too high")
 
   # Given that getStateField(pool.dag.headState, validators) is a seq,
   # signed_voluntary_exit.message.validator_index.int is already valid, but
   # check explicitly if one changes that data structure.
   if signed_voluntary_exit.message.validator_index.int in
       pool.prior_seen_voluntary_exit_indices:
-    return err((ValidationResult.Ignore, cstring(
-      "validateVoluntaryExit: validator index already voluntarily exited")))
+    return errIgnore("VoluntaryExit: validator index already voluntarily exited")
 
   # [REJECT] All of the conditions within process_voluntary_exit pass
   # validation.
diff --git a/beacon_chain/nimbus_beacon_node.nim b/beacon_chain/nimbus_beacon_node.nim
index 320b65013..8db980fd7 100644
--- a/beacon_chain/nimbus_beacon_node.nim
+++ b/beacon_chain/nimbus_beacon_node.nim
@@ -29,13 +29,15 @@ import
   ./networking/[eth2_discovery, eth2_network, network_metadata],
   ./gossip_processing/[eth2_processor, block_processor, consensus_manager],
   ./validators/[
-    attestation_aggregation, validator_duties, validator_pool,
+    validator_duties, validator_pool,
     slashing_protection, keystore_management],
   ./sync/[sync_manager, sync_protocol, request_manager],
   ./rpc/[rest_api, rpc_api],
   ./spec/datatypes/[altair, phase0],
   ./spec/eth2_apis/rpc_beacon_client,
-  ./spec/[beaconstate, forks, helpers, network, weak_subjectivity, signatures],
+  ./spec/[
+    beaconstate, forks, helpers, network, weak_subjectivity, signatures,
+    validator],
   ./consensus_object_pools/[
     blockchain_dag, block_quarantine, block_clearance, block_pools_types,
     attestation_pool, exit_pool, spec_cache],
@@ -312,7 +314,7 @@ proc init*(T: type BeaconNode,
       rng, config, netKeys, cfg, dag.forkDigests, getBeaconTime,
       getStateField(dag.headState.data, genesis_validators_root))
     attestationPool = newClone(AttestationPool.init(dag, quarantine))
-    exitPool = newClone(ExitPool.init(dag, quarantine))
+    exitPool = newClone(ExitPool.init(dag))
 
   case config.slashingDbKind
   of SlashingDbKind.v2:
@@ -1017,6 +1019,11 @@ proc onSlotEnd(node: BeaconNode, slot: Slot) {.async.} =
   if nextAttestationSlot != FAR_FUTURE_SLOT:
     next_action_wait.set(nextActionWaitTime.toFloatSeconds)
 
+  let epoch = slot.epoch
+  if epoch >= node.network.forkId.next_fork_epoch:
+    node.network.updateForkId(
+      node.dag.cfg.getENRForkID(epoch, node.dag.genesisValidatorsRoot))
+
   node.updateGossipStatus(slot)
 
   # When we're not behind schedule, we'll speculatively update the clearance
diff --git a/beacon_chain/rpc/rest_beacon_api.nim b/beacon_chain/rpc/rest_beacon_api.nim
index 4ee8bbb5a..dcea48063 100644
--- a/beacon_chain/rpc/rest_beacon_api.nim
+++ b/beacon_chain/rpc/rest_beacon_api.nim
@@ -4,9 +4,10 @@
 #   * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 import
-  std/[typetraits, sequtils, strutils, deques, sets, options],
+  std/[typetraits, sequtils, strutils, deques, sets],
   stew/[results, base10],
   chronicles,
+  json_serialization, json_serialization/std/[options, net],
   nimcrypto/utils as ncrutils,
   ../beacon_node_common, ../networking/eth2_network,
   ../consensus_object_pools/[blockchain_dag, exit_pool, spec_cache],
@@ -96,13 +97,6 @@ proc toString*(kind: ValidatorFilterKind): string =
   of ValidatorFilterKind.WithdrawalDone:
     "withdrawal_done"
 
-proc getBeaconBlocksTopic(node: BeaconNode, kind: BeaconBlockFork): string =
-  case kind
-  of BeaconBlockFork.Phase0:
-    getBeaconBlocksTopic(node.dag.forkDigests.phase0)
-  of BeaconBlockFork.Altair:
-    getBeaconBlocksTopic(node.dag.forkDigests.altair)
-
 proc installBeaconApiHandlers*(router: var RestRouter, node: BeaconNode) =
   # https://ethereum.github.io/beacon-APIs/#/Beacon/getGenesis
   router.api(MethodGet, "/api/eth/v1/beacon/genesis") do () -> RestApiResponse:
diff --git a/beacon_chain/rpc/rest_validator_api.nim b/beacon_chain/rpc/rest_validator_api.nim
index 74c8e2ca8..38b4d43ad 100644
--- a/beacon_chain/rpc/rest_validator_api.nim
+++ b/beacon_chain/rpc/rest_validator_api.nim
@@ -8,11 +8,12 @@ import
   stew/[results, base10],
   chronicles,
   nimcrypto/utils as ncrutils,
-  ../spec/datatypes/[phase0],
-  ../beacon_node_common, ../networking/eth2_network,
+  ".."/[beacon_chain_db, beacon_node_common],
+  ../networking/eth2_network,
   ../consensus_object_pools/[blockchain_dag, spec_cache, attestation_pool],
   ../validators/validator_duties,
   ../spec/[forks, network],
+  ../spec/datatypes/[phase0, altair],
   ./rest_utils
 
 logScope: topics = "rest_validatorapi"
diff --git a/beacon_chain/rpc/rpc_beacon_api.nim b/beacon_chain/rpc/rpc_beacon_api.nim
index c5c450db1..049899eb3 100644
--- a/beacon_chain/rpc/rpc_beacon_api.nim
+++ b/beacon_chain/rpc/rpc_beacon_api.nim
@@ -405,8 +405,7 @@ proc installBeaconApiHandlers*(rpcServer: RpcServer, node: BeaconNode) {.
     if head.slot >= blck.message.slot:
       # TODO altair-transition, but not immediate testnet-priority to detect
       # Altair and fail, since /v1/ doesn't support Altair
-      let blocksTopic = getBeaconBlocksTopic(node.dag.forkDigests.phase0)
-      node.network.broadcast(blocksTopic, blck)
+      node.network.broadcastBeaconBlock(ForkedSignedBeaconBlock.init(blck))
       # The block failed validation, but was successfully broadcast anyway.
       # It was not integrated into the beacon node's database.
       return 202
@@ -414,8 +413,7 @@ proc installBeaconApiHandlers*(rpcServer: RpcServer, node: BeaconNode) {.
       let res = await proposeSignedBlock(node, head, AttachedValidator(), blck)
       if res == head:
         # TODO altair-transition, but not immediate testnet-priority
-        let blocksTopic = getBeaconBlocksTopic(node.dag.forkDigests.phase0)
-        node.network.broadcast(blocksTopic, blck)
+        node.network.broadcastBeaconBlock(ForkedSignedBeaconBlock.init(blck))
         # The block failed validation, but was successfully broadcast anyway.
         # It was not integrated into the beacon node''s database.
         return 202
diff --git a/beacon_chain/rpc/rpc_validator_api.nim b/beacon_chain/rpc/rpc_validator_api.nim
index 909ebbb96..b452c5877 100644
--- a/beacon_chain/rpc/rpc_validator_api.nim
+++ b/beacon_chain/rpc/rpc_validator_api.nim
@@ -78,8 +78,7 @@ proc installValidatorApiHandlers*(rpcServer: RpcServer, node: BeaconNode) {.
   rpcServer.rpc("post_v1_validator_aggregate_and_proofs") do (
       payload: SignedAggregateAndProof) -> bool:
     debug "post_v1_validator_aggregate_and_proofs"
-    node.network.broadcast(
-      getAggregateAndProofsTopic(node.dag.forkDigests.phase0), payload)
+    node.network.broadcastAggregateAndProof(payload)
     notice "Aggregated attestation sent",
       attestation = shortLog(payload.message.aggregate),
       signature = shortLog(payload.signature)
diff --git a/beacon_chain/spec/datatypes/altair.nim b/beacon_chain/spec/datatypes/altair.nim
index c204267d9..09ccb0d9f 100644
--- a/beacon_chain/spec/datatypes/altair.nim
+++ b/beacon_chain/spec/datatypes/altair.nim
@@ -28,8 +28,8 @@
 #  stew/byteutils,
 
 import
+  std/[macros, typetraits],
   chronicles,
-  std/macros,
   stew/[assign2, bitops2],
   json_serialization/types as jsonTypes
 
diff --git a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
index 66d93dc26..4e4f5aa90 100644
--- a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
+++ b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
@@ -9,6 +9,7 @@ import
   stew/[results, base10, byteutils, endians2],
   presto,
   libp2p/peerid,
+  serialization,
   json_serialization, json_serialization/std/[options, net],
   nimcrypto/utils as ncrutils,
   ../datatypes/[phase0, altair, merge],
diff --git a/beacon_chain/spec/validator.nim b/beacon_chain/spec/validator.nim
index b19501353..a88ef258e 100644
--- a/beacon_chain/spec/validator.nim
+++ b/beacon_chain/spec/validator.nim
@@ -374,3 +374,10 @@ func get_beacon_proposer_index*(
 func get_beacon_proposer_index*(state: SomeBeaconState, cache: var StateCache):
     Option[ValidatorIndex] =
   get_beacon_proposer_index(state, cache, state.slot)
+
+# https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
+func is_aggregator*(committee_len: uint64, slot_signature: ValidatorSig): bool =
+  let
+    modulo = max(1'u64, committee_len div TARGET_AGGREGATORS_PER_COMMITTEE)
+  bytes_to_uint64(eth2digest(
+    slot_signature.toRaw()).data.toOpenArray(0, 7)) mod modulo == 0
diff --git a/beacon_chain/sync/sync_protocol.nim b/beacon_chain/sync/sync_protocol.nim
index 96e6bb222..84fc242b4 100644
--- a/beacon_chain/sync/sync_protocol.nim
+++ b/beacon_chain/sync/sync_protocol.nim
@@ -70,17 +70,13 @@ proc readChunkPayload*(conn: Connection, peer: Peer,
   if contextBytes == peer.network.forkDigests.phase0:
     let res = await readChunkPayload(conn, peer, phase0.SignedBeaconBlock)
     if res.isOk:
-      return ok ForkedSignedBeaconBlock(
-        kind: BeaconBlockFork.Phase0,
-        phase0Block: res.get)
+      return ok ForkedSignedBeaconBlock.init(res.get)
     else:
       return err(res.error)
   elif contextBytes == peer.network.forkDigests.altair:
     let res = await readChunkPayload(conn, peer, altair.SignedBeaconBlock)
     if res.isOk:
-      return ok ForkedSignedBeaconBlock(
-        kind: BeaconBlockFork.Altair,
-        altairBlock: res.get)
+      return ok ForkedSignedBeaconBlock.init(res.get)
     else:
       return err(res.error)
   else:
diff --git a/beacon_chain/validator_client/attestation_service.nim b/beacon_chain/validator_client/attestation_service.nim
index 8ae54ca02..1943d85bb 100644
--- a/beacon_chain/validator_client/attestation_service.nim
+++ b/beacon_chain/validator_client/attestation_service.nim
@@ -1,6 +1,6 @@
 import std/[sets, sequtils]
 import chronicles
-import common, api, block_service
+import "."/[common, api, block_service]
 
 logScope: service = "attestation_service"
 
diff --git a/beacon_chain/validator_client/common.nim b/beacon_chain/validator_client/common.nim
index 2270026cf..e6412ceb9 100644
--- a/beacon_chain/validator_client/common.nim
+++ b/beacon_chain/validator_client/common.nim
@@ -7,9 +7,9 @@ import chronos, presto, presto/client as presto_client, chronicles, confutils,
 # Local modules
 import
   ../spec/datatypes/[phase0, altair],
-  ../spec/[eth2_merkleization, helpers, signatures],
+  ../spec/[eth2_merkleization, helpers, signatures, validator],
   ../spec/eth2_apis/rest_beacon_client,
-  ../validators/[attestation_aggregation, keystore_management,
+  ../validators/[keystore_management,
                   validator_pool, slashing_protection],
   ".."/[conf, beacon_clock, version, beacon_node_types,
         nimbus_binary_common]
@@ -19,11 +19,11 @@ export os, tables, sequtils, sequtils, chronos, presto, chronicles, confutils,
        byteutils, presto_client
 
 export rest_beacon_client,
-       phase0, altair, helpers, signatures, eth2_merkleization,
+       phase0, altair, helpers, signatures, validator, eth2_merkleization,
        beacon_clock,
        kvstore, kvstore_sqlite3,
        keystore_management, slashing_protection, validator_pool,
-       attestation_aggregation, beacon_node_types
+       beacon_node_types
 
 const
   SYNC_TOLERANCE* = 4'u64
diff --git a/beacon_chain/validators/attestation_aggregation.nim b/beacon_chain/validators/attestation_aggregation.nim
deleted file mode 100644
index 757b21775..000000000
--- a/beacon_chain/validators/attestation_aggregation.nim
+++ /dev/null
@@ -1,50 +0,0 @@
-# beacon_chain
-# Copyright (c) 2019-2021 Status Research & Development GmbH
-# Licensed and distributed under either of
-#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
-#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
-# at your option. This file may not be copied, modified, or distributed except according to those terms.
-
-{.push raises: [Defect].}
-
-import
-  std/options,
-  ../spec/datatypes/base,
-  ../spec/[helpers],
-  ../consensus_object_pools/[spec_cache, attestation_pool]
-
-# https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
-func is_aggregator*(committee_len: uint64, slot_signature: ValidatorSig): bool =
-  let
-    modulo = max(1'u64, committee_len div TARGET_AGGREGATORS_PER_COMMITTEE)
-  bytes_to_uint64(eth2digest(
-    slot_signature.toRaw()).data.toOpenArray(0, 7)) mod modulo == 0
-
-func is_aggregator*(epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
-    slot_signature: ValidatorSig): bool =
-  let
-    committee_len = get_beacon_committee_len(epochRef, slot, index)
-  return is_aggregator(committee_len, slot_signature)
-
-proc aggregate_attestations*(
-    pool: var AttestationPool, epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
-    validatorIndex: ValidatorIndex, slot_signature: ValidatorSig): Option[AggregateAndProof] =
-  doAssert validatorIndex in get_beacon_committee(epochRef, slot, index)
-  doAssert index.uint64 < get_committee_count_per_slot(epochRef)
-
-  # TODO for testing purposes, refactor this into the condition check
-  # and just calculation
-  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
-  if not is_aggregator(epochRef, slot, index, slot_signature):
-    return none(AggregateAndProof)
-
-  let maybe_slot_attestation = getAggregatedAttestation(pool, slot, index)
-  if maybe_slot_attestation.isNone:
-    return none(AggregateAndProof)
-
-  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#construct-aggregate
-  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregateandproof
-  some(AggregateAndProof(
-    aggregator_index: validatorIndex.uint64,
-    aggregate: maybe_slot_attestation.get,
-    selection_proof: slot_signature))
diff --git a/beacon_chain/validators/validator_duties.nim b/beacon_chain/validators/validator_duties.nim
index 2c50cde61..f46da6386 100644
--- a/beacon_chain/validators/validator_duties.nim
+++ b/beacon_chain/validators/validator_duties.nim
@@ -30,9 +30,7 @@ import
   ../sszdump, ../sync/sync_manager,
   ../gossip_processing/consensus_manager,
   ".."/[conf, beacon_clock, beacon_node_common, beacon_node_types, version],
-  "."/[
-    slashing_protection, attestation_aggregation, validator_pool,
-    keystore_management]
+  "."/[slashing_protection, validator_pool, keystore_management]
 
 # Metrics for tracking attestation and beacon block loss
 const delayBuckets = [-Inf, -4.0, -2.0, -1.0, -0.5, -0.1, -0.05,
@@ -432,7 +430,7 @@ proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
     epochRef = node.dag.getEpochRef(
       attestationHead.blck, slot.compute_epoch_at_slot())
     committees_per_slot = get_committee_count_per_slot(epochRef)
-    fork = getStateField(node.dag.headState.data, fork)
+    fork = node.dag.forkAtEpoch(slot.epoch)
     genesis_validators_root =
       getStateField(node.dag.headState.data, genesis_validators_root)
 
@@ -493,6 +491,29 @@ proc handleProposal(node: BeaconNode, head: BlockRef, slot: Slot):
 
   return head
 
+proc makeAggregateAndProof*(
+    pool: var AttestationPool, epochRef: EpochRef, slot: Slot, index: CommitteeIndex,
+    validatorIndex: ValidatorIndex, slot_signature: ValidatorSig): Option[AggregateAndProof] =
+  doAssert validatorIndex in get_beacon_committee(epochRef, slot, index)
+  doAssert index.uint64 < get_committee_count_per_slot(epochRef)
+
+  # TODO for testing purposes, refactor this into the condition check
+  # and just calculation
+  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregation-selection
+  if not is_aggregator(epochRef, slot, index, slot_signature):
+    return none(AggregateAndProof)
+
+  let maybe_slot_attestation = getAggregatedAttestation(pool, slot, index)
+  if maybe_slot_attestation.isNone:
+    return none(AggregateAndProof)
+
+  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#construct-aggregate
+  # https://github.com/ethereum/consensus-specs/blob/v1.0.1/specs/phase0/validator.md#aggregateandproof
+  some(AggregateAndProof(
+    aggregator_index: validatorIndex.uint64,
+    aggregate: maybe_slot_attestation.get,
+    selection_proof: slot_signature))
+
 proc sendAggregatedAttestations(
     node: BeaconNode, aggregationHead: BlockRef, aggregationSlot: Slot) {.async.} =
   # The index is via a
@@ -505,7 +526,7 @@ proc sendAggregatedAttestations(
 
   let
     epochRef = node.dag.getEpochRef(aggregationHead, aggregationSlot.epoch)
-    fork = getStateField(node.dag.headState.data, fork)
+    fork = node.dag.forkAtEpoch(aggregationSlot.epoch)
     genesis_validators_root =
       getStateField(node.dag.headState.data, genesis_validators_root)
     committees_per_slot = get_committee_count_per_slot(epochRef)
@@ -532,8 +553,8 @@ proc sendAggregatedAttestations(
 
   for curr in zip(slotSigsData, slotSigs):
     let aggregateAndProof =
-      aggregate_attestations(node.attestationPool[], epochRef, aggregationSlot,
-                             curr[0].committee_index.CommitteeIndex,
+      makeAggregateAndProof(node.attestationPool[], epochRef, aggregationSlot,
+                            curr[0].committee_index.CommitteeIndex,
                              curr[0].validator_idx,
                              curr[1].read)
 
@@ -544,8 +565,7 @@ proc sendAggregatedAttestations(
       var signedAP = SignedAggregateAndProof(
         message: aggregateAndProof.get,
         signature: sig)
-      node.network.broadcast(
-        getAggregateAndProofsTopic(node.dag.forkDigests.phase0), signedAP)
+      node.network.broadcastAggregateAndProof(signedAP)
       notice "Aggregated attestation sent",
         attestation = shortLog(signedAP.message.aggregate),
         validator = shortLog(curr[0].v),
diff --git a/tests/test_exit_pool.nim b/tests/test_exit_pool.nim
index 939a98edf..45630ca2e 100644
--- a/tests/test_exit_pool.nim
+++ b/tests/test_exit_pool.nim
@@ -10,13 +10,13 @@
 import chronicles
 import eth/keys
 import ../beacon_chain/spec/datatypes/base
-import ../beacon_chain/consensus_object_pools/[block_quarantine, blockchain_dag, exit_pool]
+import ../beacon_chain/consensus_object_pools/[blockchain_dag, exit_pool]
 import "."/[testutil, testdbutil]
 
 proc getExitPool(): auto =
   let dag =
     init(ChainDAGRef, defaultRuntimeConfig, makeTestDB(SLOTS_PER_EPOCH * 3), {})
-  newClone(ExitPool.init(dag, QuarantineRef.init(keys.newRng())))
+  newClone(ExitPool.init(dag))
 
 suite "Exit pool testing suite":
   setup:
diff --git a/tests/test_honest_validator.nim b/tests/test_honest_validator.nim
index c01d85eaa..ff681d0cc 100644
--- a/tests/test_honest_validator.nim
+++ b/tests/test_honest_validator.nim
@@ -3,9 +3,8 @@
 import
   unittest2,
   ./testutil,
-  ../beacon_chain/spec/network,
-  ../beacon_chain/spec/datatypes/[base, altair],
-  ../beacon_chain/validators/attestation_aggregation
+  ../beacon_chain/spec/[network, validator],
+  ../beacon_chain/spec/datatypes/[base, altair]
 
 suite "Honest validator":
   var forkDigest: ForkDigest