Step-by-Step Enemy Creation

Comprehensive guide to creating a complete enemy from scratch with weapons, animations, and advanced features.

Prerequisites

• Character skeletal mesh with attack animations
• Attack animation montages with hit frames identified
• Basic understanding of Gameplay Ability System
• Unreal Engine 5.6+ installed

Step 1: Character Setup

1. Select SkeletalMesh component and set your character mesh
2. Select CapsuleComponent and adjust radius/height to fit mesh
3. Select CharacterMovement component and adjust if needed

• USECMeleeTraceComponent for hit detection
• UAbilitySystemComponent (configured)
• IAbilitySystemInterface (implemented)
• USECActionSetComponent for action set resolution and replicated action state
• USECCombatRoleComponent for replicated combat role

The controller's SECCombatControllerComponent checks the pawn for an AIConfig first. If none is set on the pawn, the component uses its own DefaultAIConfig fallback. If neither is set, there will be no AI behavior.

Not inheriting from EnemyCharacterBase? Add SECMeleeTraceComponent, SECActionSetComponent, and SECCombatRoleComponent manually. Implement IAbilitySystemInterface and set up your own AbilitySystemComponent. The system only requires these components to be present on the pawn.

Step 2: AI Controller Setup

Option A: Use EnemyControllerBase (Recommended)

// These components are created as default subobjects:
USECCombatControllerComponent*  // Combat system integration (AIConfig, roles, sync)
UMovementEvaluatorComponent*    // Tactical movement direction selection
UActionEvaluationComponent*     // Action scoring and execution
UThreatDetectionComponent*      // Player attention tracking
UBotStateTreeAIComponent*       // StateTree AI runner
UBehaviorTreeComponent*         // Helper BT for action sequences (not the BrainComponent)

Option B: Use Any AAIController + Components

Customization hooks: Subclass SECCombatControllerComponent in Blueprint and override SyncStateForCombatRole (custom role-change behavior) or HandleCombatTargetLost (custom target-loss fallback). Subclass ActionEvaluationComponent and override CanExecuteAction for custom action gating.

Step 3: Create an ActionSet

Action 1: Light Attack (Close Range)

Action 2: Heavy Attack (Medium Range)

Action 3: Defensive Retreat (When Too Close)

TagScoreMultipliers is a map of FGameplayTag to float. If the target or AI has a matching tag, the score is multiplied by that value. Use tags like State.Stunned (2.0), State.Blocking (0.3), Self.Enraged (1.5) to create context-aware behavior.

Step 4: Create Gameplay Abilities

Event ActivateAbility
  ↓
Play Montage and Wait
  • Montage: AM_LightAttack
  • Rate: 1.0
  ↓ On Completed / On Cancelled / On Interrupted
End Ability

If not inheriting from GameplayAbilityBase: You must call SendGameplayEventToActor with the AbilityEndTag in every exit path (completed, cancelled, interrupted). The ActionEvaluationComponent waits for this event to know the action finished. The built-in GA_SEC_Attack is a reference implementation that handles this correctly.

Step 5: Configure Animation Montages

1. Right-click the timeline at the attack's active frames
2. Add Notify State ➜ SECMeleeTraceWindow
3. Set the duration to cover the weapon swing (e.g., frames 10-25)
4. Optionally add a MotionWarping notify state for chase behavior during specific frames

• Socket IDs: ["Blade"] - This must match the trace socket ID registered on the weapon (see Step 6), not a skeleton socket name
• DamageConfig: DA_SwordDamage - Assign the damage configuration data asset here

Frame:     0    10    20    30    40    50
Animation: [━━━━][━━━━][━━━━][━━━━][━━━━]
           Windup Strike  Follow Recovery
Trace:          [═════════]

Step 6: Create Weapon

1. The base class does not add a mesh component by default. Add a StaticMeshComponent or SkeletalMeshComponent and set your mesh.
2. Add sockets to the weapon mesh: blade_start at the blade base, blade_end at the blade tip
3. Position sockets along the cutting edge

For different weapon types, select the trace shape that fits best. A hammer could use Sphere, a spear could use CapsuleTwoPoint with a longer radius. The FSECTraceSocket supports multiple shapes for different scenarios.

• On equip: Registers trace sockets with the character's SECMeleeTraceComponent
• During montage notify: Traces activate between sockets
• On hit: Applies damage via the SECDamageConfig assigned on the notify state

The system calls Unreal's ApplyDamage on hit. If you need a custom damage pipeline, you can listen to the delegates on SECMeleeTraceComponent and handle damage your own way.

Step 7: Create Damage Configuration

SECDamageConfig is Blueprintable. If you need additional properties (elemental types, status effects), create a Blueprint child class and add your custom fields.

Step 8: Build StateTree Logic

For most cases, use the included StateTree_SEC_Core instead of building from scratch. It handles the standard combat loop out of the box. The breakdown below is for learning or for situations where you need a fully custom tree.

StateTree: (Core)

├─ Root State
│  │
│  ├─ Combat State
│  │  • Condition: Target is valid AND role is not SEC.Role.None
│  │  │
│  │  ├─ Role State
│  │  │  • Condition: SEC.Role.* matches current role
│  │  │  └─ Linked Subtree: → StateTree_SEC_MoveAndAction
│  │
│  └─ Idle State
│     • Task: Delay 1.0

StateTree: StateTree_SEC_MoveAndAction

├─ Root State
│  • Task: Sync Action Set from Pawn
│  │
│  └─ Role State
│     • Tasks: PollTargetActor, Build Decision Context, Poll Action
│     │
│     ├─ Move State
│     │  • Task: AI Movement (Distance: 600)
│     │  └─ Transition → Action State
│     │
│     ├─ Action State
│     │  • Task: Do Action
│     │  ├─ Transition → Recovery State (Success)
│     │  └─ Transition → Role State (Failure)
│     │
│     └─ Recovery State
│        • Task: Delay Parameters.RecoveryDuration
│        └─ Transition → Role State

Step 9: Test Your Enemy

1. Drag BP_DetailedEnemy into the level
2. In Details Panel ➜ Pawn ➜ AI Controller Class ➜ set to BP_DetailedEnemyController

ActionEvaluationComponent → bDebugLog: true
MovementEvaluatorComponent → bDebugLog: true

LogEvaluation: Evaluating 3 actions for BP_DetailedEnemy_1...
LogEvaluation: [LightAttack] Dist:180 Angle:15 Score:0.95 SELECTED
LogEvaluation: [HeavyAttack] Dist:180 Angle:15 Score:0.60 (cooldown)
LogEvaluation: [QuickRetreat] Dist:180 Angle:15 Score:0.10 (too far)

• Approaches to ideal distance range
• Strafes around player
• Executes light attack when in optimal range
• Occasionally uses heavy attack with combo chaining
• Retreats if player gets too close or is attacking

Common Issues