diff --git a/Cargo.lock b/Cargo.lock
index 0222643f16..c65d4830d7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2513,6 +2513,7 @@ dependencies = [
  "sp-block-builder",
  "sp-blockchain",
  "sp-core",
+ "sp-externalities",
  "sp-inherents",
  "sp-runtime",
  "sp-state-machine",
diff --git a/crates/sp-domains-fraud-proof/src/execution_prover.rs b/crates/sp-domains-fraud-proof/src/execution_prover.rs
index 84fe2919a4..3414d1c282 100644
--- a/crates/sp-domains-fraud-proof/src/execution_prover.rs
+++ b/crates/sp-domains-fraud-proof/src/execution_prover.rs
@@ -6,13 +6,12 @@
 
 use crate::fraud_proof::ExecutionPhase;
 use domain_block_builder::create_delta_backend;
-use hash_db::HashDB;
 use sc_client_api::backend::Backend;
 use sp_api::StorageProof;
 use sp_core::traits::CodeExecutor;
 use sp_runtime::traits::{Block as BlockT, HashingFor};
 use sp_state_machine::backend::AsTrieBackend;
-use sp_trie::DBValue;
+use sp_state_machine::BackendTransaction;
 use std::marker::PhantomData;
 use std::sync::Arc;
 
@@ -40,12 +39,12 @@ where
 
     /// Returns a storage proof which can be used to reconstruct a partial state trie to re-run
     /// the execution by someone who does not own the whole state.
-    pub fn prove_execution<DB: HashDB<HashingFor<Block>, DBValue>>(
+    pub fn prove_execution(
         &self,
         at: Block::Hash,
         execution_phase: &ExecutionPhase,
         call_data: &[u8],
-        delta_changes: Option<(DB, Block::Hash)>,
+        delta_changes: Option<(BackendTransaction<HashingFor<Block>>, Block::Hash)>,
     ) -> sp_blockchain::Result<StorageProof> {
         let state = self.backend.state_at(at)?;
 
diff --git a/domains/client/block-builder/Cargo.toml b/domains/client/block-builder/Cargo.toml
index 18daefca98..5798ca4122 100644
--- a/domains/client/block-builder/Cargo.toml
+++ b/domains/client/block-builder/Cargo.toml
@@ -20,6 +20,7 @@ sp-api = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89
 sp-blockchain = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
 sp-block-builder = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
 sp-core = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
+sp-externalities = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
 sp-inherents = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
 sp-runtime = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
 sp-state-machine = { git = "https://github.com/subspace/polkadot-sdk", rev = "94a1a8143a89bbe9f938c1939ff68abc1519a305" }
diff --git a/domains/client/block-builder/src/custom_api.rs b/domains/client/block-builder/src/custom_api.rs
index f07aba67da..05dd41b94b 100644
--- a/domains/client/block-builder/src/custom_api.rs
+++ b/domains/client/block-builder/src/custom_api.rs
@@ -1,29 +1,64 @@
 //! Custom API that is efficient to collect storage roots.
 
-use codec::Codec;
+// TODO: remove in later commits
+#![allow(dead_code)]
+
+use codec::{Codec, Decode, Encode};
 use hash_db::{HashDB, Hasher, Prefix};
-use sp_state_machine::{DBValue, TrieBackend, TrieBackendBuilder, TrieBackendStorage};
+use sc_client_api::{backend, ExecutorProvider, StateBackend};
+use sp_core::traits::{CallContext, CodeExecutor, RuntimeCode};
+use sp_runtime::traits::{Block as BlockT, HashingFor, NumberFor};
+use sp_runtime::{ApplyExtrinsicResult, ExtrinsicInclusionMode, TransactionOutcome};
+use sp_state_machine::backend::AsTrieBackend;
+use sp_state_machine::{
+    BackendTransaction, DBValue, OverlayedChanges, StateMachine, StorageChanges, TrieBackend,
+    TrieBackendBuilder, TrieBackendStorage,
+};
 use std::marker::PhantomData;
+use std::sync::Arc;
+
+type TrieBackendStorageFor<State, Block> =
+    <State as StateBackend<HashingFor<Block>>>::TrieBackendStorage;
+
+type TrieDeltaBackendFor<'a, State, Block> = TrieBackend<
+    DeltaBackend<'a, TrieBackendStorageFor<State, Block>, HashingFor<Block>>,
+    HashingFor<Block>,
+>;
+
+type TrieBackendFor<State, Block> =
+    TrieBackend<TrieBackendStorageFor<State, Block>, HashingFor<Block>>;
 
 /// Create a new trie backend with memory DB delta changes.
 ///
 /// This can be used to verify any extrinsic-specific execution on the combined state of `backend`
 /// and `delta`.
-pub fn create_delta_backend<'a, S, H, DB>(
+pub fn create_delta_backend<'a, S, H>(
+    backend: &'a TrieBackend<S, H>,
+    delta: BackendTransaction<H>,
+    post_delta_root: H::Out,
+) -> TrieBackend<DeltaBackend<'a, S, H>, H>
+where
+    S: 'a + TrieBackendStorage<H>,
+    H: 'a + Hasher,
+    H::Out: Codec,
+{
+    create_delta_backend_with_maybe_delta(backend, Some(delta), post_delta_root)
+}
+
+fn create_delta_backend_with_maybe_delta<'a, S, H>(
     backend: &'a TrieBackend<S, H>,
-    delta: DB,
+    maybe_delta: Option<BackendTransaction<H>>,
     post_delta_root: H::Out,
-) -> TrieBackend<DeltaBackend<'a, S, H, DB>, H>
+) -> TrieBackend<DeltaBackend<'a, S, H>, H>
 where
     S: 'a + TrieBackendStorage<H>,
     H: 'a + Hasher,
     H::Out: Codec,
-    DB: HashDB<H, DBValue>,
 {
     let essence = backend.essence();
     let delta_backend = DeltaBackend {
         backend: essence.backend_storage(),
-        delta,
+        delta: maybe_delta,
         _phantom: PhantomData::<H>,
     };
     TrieBackendBuilder::new(delta_backend, post_delta_root).build()
@@ -31,27 +66,233 @@ where
 
 /// DeltaBackend provides the TrieBackend using main backend and some delta changes
 /// that are not part of the main backend.
-pub struct DeltaBackend<'a, S, H, DB>
+pub struct DeltaBackend<'a, S, H>
 where
     S: 'a + TrieBackendStorage<H>,
     H: 'a + Hasher,
-    DB: HashDB<H, DBValue>,
 {
     backend: &'a S,
-    delta: DB,
+    delta: Option<BackendTransaction<H>>,
     _phantom: PhantomData<H>,
 }
 
-impl<'a, S, H, DB> TrieBackendStorage<H> for DeltaBackend<'a, S, H, DB>
+impl<'a, S, H> TrieBackendStorage<H> for DeltaBackend<'a, S, H>
 where
     S: 'a + TrieBackendStorage<H>,
     H: 'a + Hasher,
-    DB: HashDB<H, DBValue>,
 {
     fn get(&self, key: &H::Out, prefix: Prefix) -> Result<Option<DBValue>, String> {
-        match HashDB::get(&self.delta, key, prefix) {
-            Some(v) => Ok(Some(v)),
-            None => Ok(self.backend.get(key, prefix)?),
+        if let Some(db) = &self.delta
+            && let Some(v) = HashDB::get(db, key, prefix)
+        {
+            Ok(Some(v))
+        } else {
+            Ok(self.backend.get(key, prefix)?)
         }
     }
 }
+
+impl<'a, S, H> DeltaBackend<'a, S, H>
+where
+    S: 'a + TrieBackendStorage<H>,
+    H: 'a + Hasher,
+{
+    fn consolidate_delta(&mut self, db: BackendTransaction<H>) {
+        let delta = if let Some(mut delta) = self.delta.take() {
+            delta.consolidate(db);
+            delta
+        } else {
+            db
+        };
+        self.delta = Some(delta);
+    }
+}
+
+pub(crate) struct TrieBackendApi<Client, Block: BlockT, Backend: backend::Backend<Block>, Exec> {
+    parent_hash: Block::Hash,
+    parent_number: NumberFor<Block>,
+    client: Arc<Client>,
+    state: Backend::State,
+    executor: Exec,
+    maybe_storage_changes: Option<StorageChanges<HashingFor<Block>>>,
+}
+
+impl<Client, Block, Backend, Exec> TrieBackendApi<Client, Block, Backend, Exec>
+where
+    Block: BlockT,
+    Backend: backend::Backend<Block>,
+    Client: ExecutorProvider<Block>,
+    Exec: CodeExecutor,
+{
+    pub(crate) fn new(
+        parent_hash: Block::Hash,
+        parent_number: NumberFor<Block>,
+        client: Arc<Client>,
+        backend: Arc<Backend>,
+        executor: Exec,
+    ) -> Result<Self, sp_blockchain::Error> {
+        let state = backend.state_at(parent_hash)?;
+        Ok(Self {
+            parent_hash,
+            parent_number,
+            client,
+            state,
+            executor,
+            maybe_storage_changes: None,
+        })
+    }
+
+    fn call_function<R: Decode>(
+        &self,
+        method: &str,
+        call_data: Vec<u8>,
+        trie_backend: &TrieDeltaBackendFor<Backend::State, Block>,
+        runtime_code: RuntimeCode,
+        overlayed_changes: &mut OverlayedChanges<HashingFor<Block>>,
+    ) -> Result<R, sp_blockchain::Error> {
+        let mut extensions = self
+            .client
+            .execution_extensions()
+            .extensions(self.parent_hash, self.parent_number);
+
+        let result = StateMachine::<_, _, _>::new(
+            trie_backend,
+            overlayed_changes,
+            &self.executor,
+            method,
+            call_data.as_slice(),
+            &mut extensions,
+            &runtime_code,
+            CallContext::Onchain,
+        )
+        .set_parent_hash(self.parent_hash)
+        .execute()?;
+
+        R::decode(&mut result.as_slice())
+            .map_err(|err| sp_blockchain::Error::CallResultDecode("failed to decode Result", err))
+    }
+
+    fn consolidate_storage_changes(&mut self, mut changes: StorageChanges<HashingFor<Block>>) {
+        let changes = if let Some(mut current_changes) = self.maybe_storage_changes.take() {
+            current_changes
+                .main_storage_changes
+                .append(&mut changes.main_storage_changes);
+            current_changes
+                .child_storage_changes
+                .append(&mut changes.child_storage_changes);
+            current_changes
+                .offchain_storage_changes
+                .append(&mut changes.offchain_storage_changes);
+            current_changes.transaction.consolidate(changes.transaction);
+            current_changes.transaction_storage_root = changes.transaction_storage_root;
+            current_changes
+                .transaction_index_changes
+                .append(&mut changes.transaction_index_changes);
+            current_changes
+        } else {
+            changes
+        };
+        self.maybe_storage_changes = Some(changes)
+    }
+
+    pub(crate) fn initialize_block(
+        &self,
+        header: Block::Header,
+        backend: &TrieDeltaBackendFor<Backend::State, Block>,
+        runtime_code: RuntimeCode,
+        overlayed_changes: &mut OverlayedChanges<HashingFor<Block>>,
+    ) -> Result<ExtrinsicInclusionMode, sp_blockchain::Error> {
+        let call_data = header.encode();
+        self.call_function(
+            "Core_initialize_block",
+            call_data,
+            backend,
+            runtime_code,
+            overlayed_changes,
+        )
+    }
+
+    pub(crate) fn apply_extrinsic(
+        &self,
+        extrinsic: <Block as BlockT>::Extrinsic,
+        backend: &TrieDeltaBackendFor<Backend::State, Block>,
+        runtime_code: RuntimeCode,
+        overlayed_changes: &mut OverlayedChanges<HashingFor<Block>>,
+    ) -> Result<ApplyExtrinsicResult, sp_blockchain::Error> {
+        let call_data = extrinsic.encode();
+        self.call_function(
+            "BlockBuilder_apply_extrinsic",
+            call_data,
+            backend,
+            runtime_code,
+            overlayed_changes,
+        )
+    }
+
+    pub(crate) fn finalize_block(
+        &self,
+        backend: &TrieDeltaBackendFor<Backend::State, Block>,
+        runtime_code: RuntimeCode,
+        overlayed_changes: &mut OverlayedChanges<HashingFor<Block>>,
+    ) -> Result<Block::Header, sp_blockchain::Error> {
+        self.call_function(
+            "BlockBuilder_finalize_block",
+            vec![],
+            backend,
+            runtime_code,
+            overlayed_changes,
+        )
+    }
+
+    pub(crate) fn execute_in_transaction<F, R>(
+        &mut self,
+        call: F,
+    ) -> Result<R, sp_blockchain::Error>
+    where
+        F: FnOnce(
+            &Self,
+            &TrieDeltaBackendFor<Backend::State, Block>,
+            RuntimeCode,
+            &mut OverlayedChanges<HashingFor<Block>>,
+        ) -> TransactionOutcome<R>,
+        R: Decode,
+    {
+        let trie_backend = self.state.as_trie_backend();
+        let state_runtime_code = sp_state_machine::backend::BackendRuntimeCode::new(trie_backend);
+        let runtime_code = state_runtime_code
+            .runtime_code()
+            .map_err(sp_blockchain::Error::RuntimeCode)?;
+        let mut overlayed_changes = OverlayedChanges::default();
+        let (state_root, delta) = if let Some(changes) = &self.maybe_storage_changes {
+            (
+                changes.transaction_storage_root,
+                Some(changes.transaction.clone()),
+            )
+        } else {
+            (*trie_backend.root(), None)
+        };
+        let trie_delta_backend =
+            create_delta_backend_with_maybe_delta(trie_backend, delta, state_root);
+
+        let outcome = call(
+            self,
+            &trie_delta_backend,
+            runtime_code,
+            &mut overlayed_changes,
+        );
+
+        let result = match outcome {
+            TransactionOutcome::Commit(result) => {
+                let state_version = sp_core::storage::StateVersion::V1;
+                let storage_changes = overlayed_changes
+                    .drain_storage_changes(&self.state, state_version)
+                    .map_err(sp_blockchain::Error::StorageChanges)?;
+                self.consolidate_storage_changes(storage_changes);
+                result
+            }
+            TransactionOutcome::Rollback(result) => result,
+        };
+
+        Ok(result)
+    }
+}
diff --git a/domains/client/block-builder/src/lib.rs b/domains/client/block-builder/src/lib.rs
index 2df5c4f910..f37c51b7e3 100644
--- a/domains/client/block-builder/src/lib.rs
+++ b/domains/client/block-builder/src/lib.rs
@@ -25,6 +25,7 @@
 //! initialize a block, to push extrinsics and to finalize a block.
 
 #![warn(missing_docs)]
+#![feature(let_chains)]
 
 mod custom_api;