diff --git a/e2e/app/setup.go b/e2e/app/setup.go
index f99066546..c4c6c9812 100644
--- a/e2e/app/setup.go
+++ b/e2e/app/setup.go
@@ -163,6 +163,7 @@ func Setup(ctx context.Context, def Definition, depCfg DeployConfig) error {
 			node.Mode,
 			omniEVM.InstanceName,
 			endpoints,
+			def.Testnet.Manifest.HaloChaos,
 		); err != nil {
 			return err
 		}
@@ -396,6 +397,7 @@ func writeHaloConfig(
 	mode e2e.Mode,
 	evmInstance string,
 	endpoints xchain.RPCEndpoints,
+	devnetChaos bool,
 ) error {
 	cfg := halocfg.DefaultConfig()
 
@@ -412,6 +414,7 @@ func writeHaloConfig(
 	cfg.EngineJWTFile = "/halo/config/jwtsecret"                    // Absolute path inside docker container
 	cfg.Tracer.Endpoint = defCfg.TracingEndpoint
 	cfg.Tracer.Headers = defCfg.TracingHeaders
+	cfg.DevnetChaos = devnetChaos
 
 	if testCfg {
 		cfg.SnapshotInterval = 1   // Write snapshots each block in e2e tests
diff --git a/e2e/manifests/ci.toml b/e2e/manifests/ci.toml
index 16436264a..560a7a382 100644
--- a/e2e/manifests/ci.toml
+++ b/e2e/manifests/ci.toml
@@ -4,6 +4,7 @@ anvil_chains = ["mock_l2", "mock_l1"]
 multi_omni_evms = true
 network_upgrade_height = 15
 pingpong_n = 5 # Increased ping pong to span validator updates
+halo_chaos = true
 
 [node.validator01]
 [node.validator02]
diff --git a/e2e/types/manifest.go b/e2e/types/manifest.go
index 563df22af..509c3986b 100644
--- a/e2e/types/manifest.go
+++ b/e2e/types/manifest.go
@@ -58,8 +58,6 @@ const (
 	PerturbStopStart Perturb = "stopstart"
 	// PerturbRollback defines a perturbation that stops a halo node, performs a rollback, then starts it again.
 	PerturbRollback Perturb = "rollback"
-	// PerturbUpgrade defines a perturbation that upgrades a halo node to the latest image tag.
-	PerturbUpgrade Perturb = "upgrade"
 
 	// PerturbFuzzyHeadDropBlocks defines a perturbation that enables fuzzyhead dropping xblock for a while.
 	PerturbFuzzyHeadDropBlocks Perturb = "fuzzyhead_dropblocks"
@@ -72,8 +70,6 @@ const (
 )
 
 // Manifest wraps e2e.Manifest with additional omni-specific fields.
-//
-
 type Manifest struct {
 	e2e.Manifest
 
@@ -118,6 +114,9 @@ type Manifest struct {
 	// NetworkUpgradeHeight defines the network upgrade height, default is genesis, negative is disabled.
 	// Note that it might be scheduled at a later height.
 	NetworkUpgradeHeight int64 `toml:"network_upgrade_height"`
+
+	// HaloChaos defines whether to enable chaos testing in halo.
+	HaloChaos bool `toml:"halo_chaos"`
 }
 
 // Seeds returns a map of seed nodes by name.
diff --git a/halo/app/abci.go b/halo/app/abci.go
index ae0ae389c..519c09412 100644
--- a/halo/app/abci.go
+++ b/halo/app/abci.go
@@ -4,7 +4,9 @@ package app
 import (
 	"context"
 	"fmt"
+	"time"
 
+	"github.com/omni-network/omni/halo/attest/types"
 	"github.com/omni-network/omni/lib/log"
 
 	abci "github.com/cometbft/cometbft/abci/types"
@@ -21,17 +23,25 @@ type abciWrapper struct {
 	abci.Application
 	postFinalize       postFinalizeCallback
 	multiStoreProvider multiStoreProvider
+	chaos              chaos
 }
 
 func newABCIWrapper(
 	app abci.Application,
 	finaliseCallback postFinalizeCallback,
 	multiStoreProvider multiStoreProvider,
+	chaosTest bool,
 ) *abciWrapper {
+	chaos := chaos(new(noopChaos))
+	if chaosTest {
+		chaos = new(chaosSlasher)
+	}
+
 	return &abciWrapper{
 		Application:        app,
 		postFinalize:       finaliseCallback,
 		multiStoreProvider: multiStoreProvider,
+		chaos:              chaos,
 	}
 }
 
@@ -65,6 +75,8 @@ func (l abciWrapper) InitChain(ctx context.Context, chain *abci.RequestInitChain
 }
 
 func (l abciWrapper) PrepareProposal(ctx context.Context, proposal *abci.RequestPrepareProposal) (*abci.ResponsePrepareProposal, error) {
+	l.chaos.PrepareProposal(ctx, proposal)
+
 	ctx = log.WithCtx(ctx, "height", proposal.Height)
 	log.Debug(ctx, "👾 ABCI call: PrepareProposal",
 		log.Hex7("proposer", proposal.ProposerAddress),
@@ -91,6 +103,8 @@ func (l abciWrapper) ProcessProposal(ctx context.Context, proposal *abci.Request
 }
 
 func (l abciWrapper) FinalizeBlock(ctx context.Context, req *abci.RequestFinalizeBlock) (*abci.ResponseFinalizeBlock, error) {
+	l.chaos.FinalizeBlock(ctx, req)
+
 	ctx = log.WithCtx(ctx, "height", req.Height)
 	resp, err := l.Application.FinalizeBlock(ctx, req)
 	if err != nil {
@@ -179,3 +193,73 @@ func (l abciWrapper) ApplySnapshotChunk(ctx context.Context, chunk *abci.Request
 	log.Debug(ctx, "👾 ABCI call: ApplySnapshotChunk")
 	return l.Application.ApplySnapshotChunk(ctx, chunk)
 }
+
+// chaos abstracts a source of chaos testing.
+type chaos interface {
+	PrepareProposal(ctx context.Context, proposal *abci.RequestPrepareProposal)
+	FinalizeBlock(ctx context.Context, req *abci.RequestFinalizeBlock)
+}
+
+// noopChaos is a no-op chaos implementation.
+// This is used in production to disable chaos testing.
+type noopChaos struct{}
+
+func (noopChaos) PrepareProposal(context.Context, *abci.RequestPrepareProposal) {}
+func (noopChaos) FinalizeBlock(context.Context, *abci.RequestFinalizeBlock)     {}
+
+const chaosSlashMinHeight = 10
+
+// chaosSlasher is a chaos implementation that slashes the first validator to vote.
+type chaosSlasher struct {
+	val         abci.Validator
+	valDetected bool
+	valSlashed  bool
+}
+
+// PrepareProposal detects the first validator to vote as slashable.
+func (c *chaosSlasher) PrepareProposal(ctx context.Context, proposal *abci.RequestPrepareProposal) {
+	if c.valDetected {
+		return
+	}
+
+	for _, vote := range proposal.LocalLastCommit.Votes {
+		votes, ok, _ := types.VotesFromExtension(vote.VoteExtension)
+		if ok && len(votes.Votes) > 0 {
+			c.val = vote.Validator
+			c.valDetected = true
+			log.Warn(ctx, "😱 Chaos slashable validator detected", nil, log.Hex7("val", c.val.Address), "height", proposal.Height)
+
+			return
+		}
+	}
+}
+
+// FinalizeBlock slashes the detected validator once.
+func (c *chaosSlasher) FinalizeBlock(ctx context.Context, req *abci.RequestFinalizeBlock) {
+	if !c.valDetected || c.valSlashed || req.Height < chaosSlashMinHeight {
+		return
+	}
+
+	// Wait for all validators to be online
+	for _, vote := range req.DecidedLastCommit.Votes {
+		if vote.BlockIdFlag != cmtproto.BlockIDFlagCommit {
+			return
+		}
+	}
+
+	var totalPower int64
+	for _, vote := range req.DecidedLastCommit.Votes {
+		totalPower += vote.Validator.Power
+	}
+
+	req.Misbehavior = append(req.Misbehavior, abci.Misbehavior{
+		Type:             abci.MisbehaviorType_DUPLICATE_VOTE,
+		Validator:        c.val,
+		Height:           req.Height - 1,
+		Time:             time.Now().Add(-time.Second),
+		TotalVotingPower: totalPower,
+	})
+
+	c.valSlashed = true
+	log.Warn(ctx, "😱 Chaos slashing validator", nil, log.Hex7("val", c.val.Address), "height", req.Height)
+}
diff --git a/halo/app/start.go b/halo/app/start.go
index 7d69dace4..99090be08 100644
--- a/halo/app/start.go
+++ b/halo/app/start.go
@@ -56,6 +56,11 @@ type Config struct {
 	Comet cmtcfg.Config
 }
 
+// ChaosTest returns true if the devnet chaos test is enabled.
+func (c Config) ChaosTest() bool {
+	return c.Network == netconf.Devnet && c.DevnetChaos
+}
+
 // BackendType returns the halo config backend type
 // or the comet backend type otherwise.
 func (c Config) BackendType() dbm.BackendType {
@@ -166,7 +171,7 @@ func Start(ctx context.Context, cfg Config) (<-chan error, func(context.Context)
 	app.EVMEngKeeper.SetBuildDelay(cfg.EVMBuildDelay)
 	app.EVMEngKeeper.SetBuildOptimistic(cfg.EVMBuildOptimistic)
 
-	cmtNode, err := newCometNode(ctx, &cfg.Comet, app, privVal)
+	cmtNode, err := newCometNode(ctx, cfg, app, privVal)
 	if err != nil {
 		return nil, nil, errors.Wrap(err, "create comet node")
 	}
@@ -294,39 +299,49 @@ func startRPCServers(
 	return nil
 }
 
-func newCometNode(ctx context.Context, cfg *cmtcfg.Config, app *App, privVal cmttypes.PrivValidator) (
-	*node.Node, error) {
-	nodeKey, err := p2p.LoadOrGenNodeKey(cfg.NodeKeyFile())
+func newCometNode(
+	ctx context.Context,
+	cfg Config,
+	app *App,
+	privVal cmttypes.PrivValidator,
+) (*node.Node, error) {
+	cmtCfg := &cfg.Comet
+	nodeKey, err := p2p.LoadOrGenNodeKey(cmtCfg.NodeKeyFile())
 	if err != nil {
-		return nil, errors.Wrap(err, "load or gen node key", "key_file", cfg.NodeKeyFile())
+		return nil, errors.Wrap(err, "load or gen node key", "key_file", cmtCfg.NodeKeyFile())
 	}
 
-	cmtLog, err := NewCmtLogger(ctx, cfg.LogLevel)
+	cmtLog, err := NewCmtLogger(ctx, cmtCfg.LogLevel)
 	if err != nil {
 		return nil, err
 	}
 
+	if cfg.ChaosTest() {
+		log.Warn(ctx, "😱 Chaos testing enabled!", nil)
+	}
+
 	wrapper := newABCIWrapper(
 		sdkserver.NewCometABCIWrapper(app),
 		app.EVMEngKeeper.PostFinalize,
 		func() storetypes.CacheMultiStore {
 			return app.CommitMultiStore().CacheMultiStore()
 		},
+		cfg.ChaosTest(),
 	)
 
 	// Configure CometBFT prometheus metrics as per provided config
 	metrics := node.DefaultMetricsProvider(&cmtcfg.InstrumentationConfig{
-		Prometheus: cfg.Instrumentation.Prometheus,
-		Namespace:  cfg.Instrumentation.Namespace,
+		Prometheus: cmtCfg.Instrumentation.Prometheus,
+		Namespace:  cmtCfg.Instrumentation.Namespace,
 	})
 	// But don't instantiate the CometBFT prometheus server, we do it startMonitoringAPI.
-	cfg.Instrumentation.Prometheus = false
+	cmtCfg.Instrumentation.Prometheus = false
 
-	cmtNode, err := node.NewNode(cfg,
+	cmtNode, err := node.NewNode(cmtCfg,
 		privVal,
 		nodeKey,
 		proxy.NewLocalClientCreator(wrapper),
-		node.DefaultGenesisDocProviderFunc(cfg),
+		node.DefaultGenesisDocProviderFunc(cmtCfg),
 		cmtcfg.DefaultDBProvider,
 		metrics,
 		cmtLog,
diff --git a/halo/attest/keeper/cpayload.go b/halo/attest/keeper/cpayload.go
index f4db947b1..da4d33903 100644
--- a/halo/attest/keeper/cpayload.go
+++ b/halo/attest/keeper/cpayload.go
@@ -18,7 +18,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
-	"github.com/cosmos/gogoproto/proto"
 )
 
 var _ evmenginetypes.VoteExtensionProvider = (*Keeper)(nil)
@@ -26,8 +25,8 @@ var _ evmenginetypes.VoteExtensionProvider = (*Keeper)(nil)
 // PrepareVotes returns the cosmosSDK transaction MsgAddVotes that will include all the validator votes included
 // in the previous block's vote extensions into the attest module.
 //
-// Note that the commit is assumed to be valid and only contains valid VEs from the previous block as
-// provided by a trusted cometBFT. Some votes (contained inside VE) may however be invalid, they are discarded.
+// Note that the commit is expected to be valid and only contains valid VEs from the previous block as
+// provided by a trusted cometBFT. Some votes (contained inside VEs) may however be invalid, they are discarded.
 func (k *Keeper) PrepareVotes(ctx context.Context, commit abci.ExtendedCommitInfo, commitHeight uint64) ([]sdk.Msg, error) {
 	sdkCtx := sdk.UnwrapSDKContext(ctx)
 	// The VEs in LastLocalCommit is expected to be valid
@@ -114,17 +113,3 @@ func sortAggregates(aggs []*types.AggVote) []*types.AggVote {
 
 	return aggs
 }
-
-// votesFromExtension returns the attestations contained in the vote extension, or false if none or an error.
-func votesFromExtension(voteExtension []byte) (*types.Votes, bool, error) {
-	if len(voteExtension) == 0 {
-		return nil, false, nil
-	}
-
-	resp := new(types.Votes)
-	if err := proto.Unmarshal(voteExtension, resp); err != nil {
-		return nil, false, errors.Wrap(err, "decode vote extension")
-	}
-
-	return resp, true, nil
-}
diff --git a/halo/attest/keeper/keeper.go b/halo/attest/keeper/keeper.go
index c7ad7e3ad..fbc0a41a8 100644
--- a/halo/attest/keeper/keeper.go
+++ b/halo/attest/keeper/keeper.go
@@ -769,7 +769,7 @@ func (k *Keeper) parseAndVerifyVoteExtension(
 		return nil, false, err // This error should never occur
 	}
 
-	votes, ok, err := votesFromExtension(voteExt)
+	votes, ok, err := types.VotesFromExtension(voteExt)
 	if err != nil {
 		return nil, false, errors.Wrap(err, "votes from extension")
 	} else if !ok {
diff --git a/halo/attest/types/helper.go b/halo/attest/types/helper.go
index 9a6f7e284..86567ed9a 100644
--- a/halo/attest/types/helper.go
+++ b/halo/attest/types/helper.go
@@ -5,7 +5,10 @@ import (
 	"log/slog"
 	"strconv"
 
+	"github.com/omni-network/omni/lib/errors"
 	"github.com/omni-network/omni/lib/xchain"
+
+	"github.com/cosmos/gogoproto/proto"
 )
 
 const logLimit = 5
@@ -45,3 +48,17 @@ func AttLogs(headers []*AttestHeader) []any {
 
 	return attrs
 }
+
+// VotesFromExtension returns the attestations contained in the vote extension, or false if none or an error.
+func VotesFromExtension(voteExtension []byte) (*Votes, bool, error) {
+	if len(voteExtension) == 0 {
+		return nil, false, nil
+	}
+
+	resp := new(Votes)
+	if err := proto.Unmarshal(voteExtension, resp); err != nil {
+		return nil, false, errors.Wrap(err, "decode vote extension")
+	}
+
+	return resp, true, nil
+}
diff --git a/halo/cmd/cmd_internal_test.go b/halo/cmd/cmd_internal_test.go
index 906879661..761c3e605 100644
--- a/halo/cmd/cmd_internal_test.go
+++ b/halo/cmd/cmd_internal_test.go
@@ -145,6 +145,7 @@ func TestTomlConfig(t *testing.T) {
 	var expect halocfg.Config
 	fuzzer.Fuzz(&expect)
 	expect.HomeDir = dir
+	expect.DevnetChaos = false // Chaos not included in toml
 
 	// The Toml library converts map keys to lower case. So do this so expect==actual.
 	for k := range expect.RPCEndpoints {
diff --git a/halo/cmd/flags.go b/halo/cmd/flags.go
index eaf1583da..7450babc0 100644
--- a/halo/cmd/flags.go
+++ b/halo/cmd/flags.go
@@ -35,6 +35,7 @@ func bindRunFlags(cmd *cobra.Command, cfg *halocfg.Config) {
 	flags.DurationVar(&cfg.EVMBuildDelay, "evm-build-delay", cfg.EVMBuildDelay, "Minimum delay between triggering and fetching a EVM payload build")
 	flags.BoolVar(&cfg.EVMBuildOptimistic, "evm-build-optimistic", cfg.EVMBuildOptimistic, "Enables optimistic building of EVM payloads on previous block finalize")
 	flags.IntSliceVar(&cfg.UnsafeSkipUpgrades, sdkserver.FlagUnsafeSkipUpgrades, cfg.UnsafeSkipUpgrades, "Skip a set of upgrade heights to continue the old binary")
+	flags.BoolVar(&cfg.DevnetChaos, "devnet-chaos-test", cfg.DevnetChaos, "Enable chaos testing (only applicable to devnet)")
 }
 
 func bindRollbackFlags(flags *pflag.FlagSet, cfg *app.RollbackConfig) {
diff --git a/halo/cmd/testdata/TestCLIReference_rollback.golden b/halo/cmd/testdata/TestCLIReference_rollback.golden
index 2a268fd59..522f69f5a 100644
--- a/halo/cmd/testdata/TestCLIReference_rollback.golden
+++ b/halo/cmd/testdata/TestCLIReference_rollback.golden
@@ -14,6 +14,7 @@ Flags:
       --api-address string                        Address defines the API server to listen on (default "tcp://0.0.0.0:1317")
       --api-enable                                Enable defines if the API server should be enabled. (default true)
       --app-db-backend string                     The type of database for application and snapshots databases (default "goleveldb")
+      --devnet-chaos-test                         Enable chaos testing (only applicable to devnet)
       --engine-endpoint string                    An EVM execution client Engine API http endpoint
       --engine-jwt-file string                    The path to the Engine API JWT file
       --evm-build-delay duration                  Minimum delay between triggering and fetching a EVM payload build (default 600ms)
diff --git a/halo/cmd/testdata/TestCLIReference_run.golden b/halo/cmd/testdata/TestCLIReference_run.golden
index e3dae2373..403e71fe5 100644
--- a/halo/cmd/testdata/TestCLIReference_run.golden
+++ b/halo/cmd/testdata/TestCLIReference_run.golden
@@ -7,6 +7,7 @@ Flags:
       --api-address string                        Address defines the API server to listen on (default "tcp://0.0.0.0:1317")
       --api-enable                                Enable defines if the API server should be enabled. (default true)
       --app-db-backend string                     The type of database for application and snapshots databases (default "goleveldb")
+      --devnet-chaos-test                         Enable chaos testing (only applicable to devnet)
       --engine-endpoint string                    An EVM execution client Engine API http endpoint
       --engine-jwt-file string                    The path to the Engine API JWT file
       --evm-build-delay duration                  Minimum delay between triggering and fetching a EVM payload build (default 600ms)
diff --git a/halo/cmd/testdata/TestRunCmd_defaults.golden b/halo/cmd/testdata/TestRunCmd_defaults.golden
index 58836fa5f..7d39b7567 100644
--- a/halo/cmd/testdata/TestRunCmd_defaults.golden
+++ b/halo/cmd/testdata/TestRunCmd_defaults.golden
@@ -24,6 +24,7 @@
   "Enable": true,
   "Address": "0.0.0.0:9090"
  },
+ "DevnetChaos": false,
  "Comet": {
   "Version": "0.38.15",
   "RootDir": "./halo",
diff --git a/halo/cmd/testdata/TestRunCmd_flags.golden b/halo/cmd/testdata/TestRunCmd_flags.golden
index 7fcfe68db..d59a68450 100644
--- a/halo/cmd/testdata/TestRunCmd_flags.golden
+++ b/halo/cmd/testdata/TestRunCmd_flags.golden
@@ -24,6 +24,7 @@
   "Enable": true,
   "Address": "0.0.0.0:9090"
  },
+ "DevnetChaos": false,
  "Comet": {
   "Version": "0.38.15",
   "RootDir": "foo",
diff --git a/halo/cmd/testdata/TestRunCmd_json_files.golden b/halo/cmd/testdata/TestRunCmd_json_files.golden
index 717562c29..5c384c614 100644
--- a/halo/cmd/testdata/TestRunCmd_json_files.golden
+++ b/halo/cmd/testdata/TestRunCmd_json_files.golden
@@ -24,6 +24,7 @@
   "Enable": true,
   "Address": "0.0.0.0:9090"
  },
+ "DevnetChaos": false,
  "Comet": {
   "Version": "0.38.15",
   "RootDir": "testinput/input2",
diff --git a/halo/cmd/testdata/TestRunCmd_toml_files.golden b/halo/cmd/testdata/TestRunCmd_toml_files.golden
index f965ef408..5436cc4ac 100644
--- a/halo/cmd/testdata/TestRunCmd_toml_files.golden
+++ b/halo/cmd/testdata/TestRunCmd_toml_files.golden
@@ -27,6 +27,7 @@
   "Enable": true,
   "Address": "grpc/toml"
  },
+ "DevnetChaos": false,
  "Comet": {
   "Version": "0.38.15",
   "RootDir": "testinput/input1",
diff --git a/halo/config/config.go b/halo/config/config.go
index 062275b32..335c64c7b 100644
--- a/halo/config/config.go
+++ b/halo/config/config.go
@@ -86,6 +86,7 @@ type Config struct {
 	UnsafeSkipUpgrades []int
 	SDKAPI             RPCConfig `mapstructure:"api"`
 	SDKGRPC            RPCConfig `mapstructure:"grpc"`
+	DevnetChaos        bool
 }
 
 // RPCConfig is an abridged version of CosmosSDK srvconfig.API/GRPCConfig.