ue-gameplay-abilities

UE Gameplay Ability System

Target engine: UE 5.8. APIs below are verified against the 5.8 headers; older forms are listed under "Deprecated — do not use".

GAS ships as the GameplayAbilities plugin (Engine/Plugins/Runtime/GameplayAbilities), which is production-ready, not Experimental. Enable it in the .uproject, then add "GameplayAbilities", "GameplayTags" and "GameplayTasks" to PublicDependencyModuleNames in your module's Build.cs. This skill covers UAbilitySystemComponent, UGameplayAbility, UGameplayEffect, UAttributeSet, UAbilityTask and Gameplay Cues.

Context

Read .agents/ue-project-context.md if it exists (module names, conventions, enabled plugins, GAS/networking setup). Do not stop if it is missing.

Identify the area from the request and the codebase. Ask only when two plausible readings would produce different code.

Request is about…	Go to
Where the ASC lives, init order, respawn, replication mode	ASC Ownership and Initialization
Writing an ability, activation, cost, cooldown, policies	Gameplay Abilities
Waiting on montages, events, targeting, timers, tag queries	Ability Tasks
Damage, buffs, stacking, executions, immunity, GE components	Gameplay Effects
Health/mana floats, clamping, attribute replication	Attribute Sets
Tags that block, grant or cancel abilities; loose tags	Tags in GAS
Particles, sounds, hit impacts, cue notify classes	Gameplay Cues
Cue scan paths, global curve tables, project config	Project Settings

GAS Architecture

Pillar	Class	Header	Purpose
Component	UAbilitySystemComponent	AbilitySystemComponent.h	Owns abilities, effects, attributes, tags
Abilities	UGameplayAbility	Abilities/GameplayAbility.h	What happens when activated
Effects	UGameplayEffect	GameplayEffect.h	Data-driven attribute mutation
Attributes	UAttributeSet	AttributeSet.h	Replicated FGameplayAttributeData stats
Tasks	UAbilityTask	Abilities/Tasks/AbilityTask.h	Latent steps inside an ability

Gameplay tags thread through all of them as requirements, grants and blockers.

ASC Ownership and Initialization

Owner	When	Notes
APlayerState	Networked player characters	ASC survives pawn death; use Mixed replication
APawn / ACharacter	AI, single-player	Simplest; use Minimal for AI, Full if a pawn-owned ASC needs full data on all clients

Every actor that owns or exposes an ASC implements IAbilitySystemInterface:

// MyCharacter.h
#pragma once

#include "GameFramework/Character.h"
#include "AbilitySystemInterface.h"
#include "MyCharacter.generated.h"

class UAbilitySystemComponent;

UCLASS()
class MYGAME_API AMyCharacter : public ACharacter, public IAbilitySystemInterface
{
    GENERATED_BODY()

public:
    AMyCharacter();

    virtual UAbilitySystemComponent* GetAbilitySystemComponent() const override;

protected:
    UPROPERTY(VisibleAnywhere, BlueprintReadOnly, Category = "GAS")
    TObjectPtr<UAbilitySystemComponent> AbilitySystemComponent;
};

// MyCharacter.cpp
#include "MyCharacter.h"
#include "AbilitySystemComponent.h"

AMyCharacter::AMyCharacter()
{
    AbilitySystemComponent = CreateDefaultSubobject<UAbilitySystemComponent>(TEXT("AbilitySystemComponent"));
    AbilitySystemComponent->SetIsReplicated(true);
    AbilitySystemComponent->SetReplicationMode(EGameplayEffectReplicationMode::Mixed);
}

UAbilitySystemComponent* AMyCharacter::GetAbilitySystemComponent() const
{
    return AbilitySystemComponent;
}

InitAbilityActorInfo(OwnerActor, AvatarActor) must run on both server and client. For a pawn-owned ASC that is BeginPlay with (this, this). For a PlayerState-owned ASC it is PossessedBy on the server and OnRep_PlayerState on the client, with (PlayerState, Character). Full dual-path code, respawn handling and the AI variant are in gas-setup-patterns.md.

EGameplayEffectReplicationMode	Effect on simulated proxies
Minimal	No GE replication; minimal tag/cue data only. AI and non-player actors
Mixed	Full GEs to the owning connection, minimal to everyone else. Player characters
Full	Every GE replicates to every client

Mixed sends full GE data to the connection that owns the ASC's owner actor (GameplayEffect.cpp:5240), so it works for a PlayerState-owned ASC and for a pawn-owned ASC once a PlayerController possesses the pawn. Choosing Full over Mixed is a bandwidth decision, not a correctness one. Minimal does not work for player-owned ASCs (AbilitySystemComponent.h:83). See ue-networking-replication for what each mode costs on the wire.

Gameplay Abilities

// MyFireballAbility.h
#pragma once

#include "Abilities/GameplayAbility.h"
#include "MyFireballAbility.generated.h"

class UGameplayEffect;

UCLASS()
class MYGAME_API UMyFireballAbility : public UGameplayAbility
{
    GENERATED_BODY()

public:
    UMyFireballAbility();

    virtual bool CanActivateAbility(const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayTagContainer* SourceTags = nullptr,
        const FGameplayTagContainer* TargetTags = nullptr,
        OUT FGameplayTagContainer* OptionalRelevantTags = nullptr) const override;

    virtual void ActivateAbility(const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayAbilityActivationInfo ActivationInfo,
        const FGameplayEventData* TriggerEventData) override;

    virtual void EndAbility(const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayAbilityActivationInfo ActivationInfo,
        bool bReplicateEndAbility, bool bWasCancelled) override;

    virtual void CancelAbility(const FGameplayAbilitySpecHandle Handle,
        const FGameplayAbilityActorInfo* ActorInfo,
        const FGameplayAbilityActivationInfo ActivationInfo,
        bool bReplicateCancelAbility) override;

protected:
    UPROPERTY(EditDefaultsOnly, Category = "GAS")
    TSubclassOf<UGameplayEffect> DamageEffect;
};

Constructor sets the policies and the ability's own tags:

// MyFireballAbility.cpp
#include "MyFireballAbility.h"
#include "AbilitySystemBlueprintLibrary.h"
#include "AbilitySystemComponent.h"

UMyFireballAbility::UMyFireballAbility()
{
    InstancingPolicy = EGameplayAbilityInstancingPolicy::InstancedPerActor;
    NetExecutionPolicy = EGameplayAbilityNetExecutionPolicy::LocalPredicted;
    NetSecurityPolicy = EGameplayAbilityNetSecurityPolicy::ClientOrServer;

    FGameplayTagContainer Tags;
    Tags.AddTag(FGameplayTag::RequestGameplayTag(TEXT("Ability.Skill.Fireball")));
    SetAssetTags(Tags);

    ActivationOwnedTags.AddTag(FGameplayTag::RequestGameplayTag(TEXT("Ability.Active.Casting")));
    ActivationBlockedTags.AddTag(FGameplayTag::RequestGameplayTag(TEXT("State.Stunned")));
    CancelAbilitiesWithTag.AddTag(FGameplayTag::RequestGameplayTag(TEXT("Ability.Active.Melee")));
}

SetAssetTags is constructor-only; read them back with GetAssetTags().

Enum	Values	Use
EGameplayAbilityInstancingPolicy	InstancedPerActor, InstancedPerExecution	InstancedPerActor is the default choice; per-execution when several copies may run at once
EGameplayAbilityNetExecutionPolicy	LocalPredicted, LocalOnly, ServerInitiated, ServerOnly	LocalPredicted for responsive player abilities
EGameplayAbilityNetSecurityPolicy	ClientOrServer, ServerOnlyExecution, ServerOnlyTermination, ServerOnly	Rejects client requests the server should own

void UMyFireballAbility::ActivateAbility(const FGameplayAbilitySpecHandle Handle,
    const FGameplayAbilityActorInfo* ActorInfo,
    const FGameplayAbilityActivationInfo ActivationInfo,
    const FGameplayEventData* TriggerEventData)
{
    Super::ActivateAbility(Handle, ActorInfo, ActivationInfo, TriggerEventData);

    // CommitAbility applies cost and cooldown; it fails if either cannot be paid.
    if (!CommitAbility(Handle, ActorInfo, ActivationInfo))
    {
        EndAbility(Handle, ActorInfo, ActivationInfo, true, true);
        return;
    }

    const FGameplayEffectSpecHandle Spec =
        MakeOutgoingGameplayEffectSpec(DamageEffect, GetAbilityLevel());
    const FGameplayAbilityTargetDataHandle TargetData =
        UAbilitySystemBlueprintLibrary::AbilityTargetDataFromActor(ActorInfo->AvatarActor.Get());

    ApplyGameplayEffectSpecToTarget(Handle, ActorInfo, ActivationInfo, Spec, TargetData);
    EndAbility(Handle, ActorInfo, ActivationInfo, true, false);
}

Split the commit when the two halves must happen at different times: CommitAbilityCost(Handle, ActorInfo, ActivationInfo) and CommitAbilityCooldown(Handle, ActorInfo, ActivationInfo, ForceCooldown) — note the cooldown overload takes the extra const bool ForceCooldown.

Inside an instanced ability, GetAbilitySystemComponentFromActorInfo_Ensured() returns the ASC and logs an ensure instead of crashing when actor info is not set up.

Granting and activating, from the server:

const FGameplayAbilitySpecHandle Handle =
    ASC->GiveAbility(FGameplayAbilitySpec(UMyFireballAbility::StaticClass(), 1));

ASC->TryActivateAbility(Handle);
ASC->TryActivateAbilityByClass(UMyFireballAbility::StaticClass());
ASC->TryActivateAbilitiesByTag(
    FGameplayTagContainer(FGameplayTag::RequestGameplayTag(TEXT("Ability.Skill.Fireball"))));
ASC->ClearAbility(Handle);

Ability Tasks

Ability tasks make an ability span frames. The pattern is always: static factory → bind delegates → ReadyForActivation() (inherited from UGameplayTask). Task delegates are dynamic, so each handler needs UFUNCTION():

// In the ability's header:
UFUNCTION()
void HandleMontageCompleted();

UFUNCTION()
void HandleMontageInterrupted();

#include "Abilities/Tasks/AbilityTask_PlayMontageAndWait.h"

UAbilityTask_PlayMontageAndWait* Task =
    UAbilityTask_PlayMontageAndWait::CreatePlayMontageAndWaitProxy(
        this, NAME_None, AttackMontage, 1.f);
Task->OnCompleted.AddDynamic(this, &UMyFireballAbility::HandleMontageCompleted);
Task->OnInterrupted.AddDynamic(this, &UMyFireballAbility::HandleMontageInterrupted);
Task->ReadyForActivation();

Task	Waits for
UAbilityTask_PlayMontageAndWait	An UAnimMontage to finish, blend out, interrupt or cancel
UAbilityTask_PlayAnimAndWait	A raw UAnimSequence played into a slot, for linked anim layers
UAbilityTask_WaitGameplayEvent	A gameplay event tag sent to the ASC (anim notify, hit registration)
UAbilityTask_WaitDelay	A fixed number of seconds
UAbilityTask_WaitTargetData	An AGameplayAbilityTargetActor to confirm targets
UAbilityTask_WaitAttributeChange / ...ChangeThreshold	An attribute to change or cross a comparison
UAbilityTask_WaitGameplayTagQuery	An FGameplayTagQuery over the target's tags to become true or false
UAbilityTask_WaitGameplayTagCountChanged	The count of one tag on the ASC to change
UAbilityTask_WaitGameplayEffectApplied_Self / _Target	A GE matching tag requirements (or an FGameplayTagQuery via the _Query factories)

Full factory signatures, delegate names, the custom-task template and the task pitfalls are in ability-task-reference.md.

Gameplay Effects

EGameplayEffectDurationType	Behaviour
Instant	Executes once against the base value; fires PostGameplayEffectExecute
HasDuration	Aggregates onto the current value for DurationMagnitude seconds
Infinite	Aggregates until removed explicitly

const FGameplayEffectContextHandle Ctx = ASC->MakeEffectContext();
const FGameplayEffectSpecHandle Spec =
    ASC->MakeOutgoingSpec(UMyDamageEffect::StaticClass(), Level, Ctx);

Spec.Data->SetSetByCallerMagnitude(
    FGameplayTag::RequestGameplayTag(TEXT("SetByCaller.Damage")), 75.f);

ASC->ApplyGameplayEffectSpecToSelf(*Spec.Data.Get());
ASC->ApplyGameplayEffectSpecToTarget(*Spec.Data.Get(), TargetASC);

ASC->RemoveActiveGameplayEffect(ActiveHandle);
ASC->RemoveActiveGameplayEffectBySourceEffect(UMyDamageEffect::StaticClass(), nullptr);

Modifier ops live in EGameplayModOp (a namespaced enum, so values are TEnumAsByte<EGameplayModOp::Type>). The aggregation equation is ((BaseValue + AddBase) * MultiplyAdditive / DivideAdditive * MultiplyCompound) + AddFinal.

Value	Meaning
AddBase	Added to the base before anything else
MultiplyAdditive	Multipliers summed, then multiplied against the running result
DivideAdditive	Divisors summed, then divided against the running result
MultiplyCompound	Multiplied into the running result, compounding with other compounds
AddFinal	Added after all multiplication
Override	Replaces the computed value

Behaviour that used to be monolithic properties on UGameplayEffect now lives in UGameplayEffectComponent subclasses under GameplayEffectComponents/. Stacking, magnitude calculations, UGameplayEffectExecutionCalculation, periodic effects, immunity, queries, lifecycle delegates and the full component list are in gameplay-effect-reference.md.

Attribute Sets

// MyHealthSet.h
#pragma once

#include "AttributeSet.h"
#include "AbilitySystemComponent.h"
#include "MyHealthSet.generated.h"

UCLASS()
class MYGAME_API UMyHealthSet : public UAttributeSet
{
    GENERATED_BODY()

public:
    UMyHealthSet();

    virtual void PreAttributeChange(const FGameplayAttribute& Attribute, float& NewValue) override;
    virtual void PostGameplayEffectExecute(const struct FGameplayEffectModCallbackData& Data) override;
    virtual void GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const override;

    UPROPERTY(BlueprintReadOnly, ReplicatedUsing = OnRep_Health, Category = "Health")
    FGameplayAttributeData Health;
    ATTRIBUTE_ACCESSORS_BASIC(UMyHealthSet, Health)

    UPROPERTY(BlueprintReadOnly, ReplicatedUsing = OnRep_MaxHealth, Category = "Health")
    FGameplayAttributeData MaxHealth;
    ATTRIBUTE_ACCESSORS_BASIC(UMyHealthSet, MaxHealth)

protected:
    UFUNCTION()
    void OnRep_Health(const FGameplayAttributeData& OldHealth);

    UFUNCTION()
    void OnRep_MaxHealth(const FGameplayAttributeData& OldMaxHealth);
};

ATTRIBUTE_ACCESSORS_BASIC generates GetHealthAttribute(), GetHealth(), SetHealth() and InitHealth(). Projects that want extra accessors define their own macro chaining GAMEPLAYATTRIBUTE_PROPERTY_GETTER, GAMEPLAYATTRIBUTE_VALUE_GETTER, GAMEPLAYATTRIBUTE_VALUE_SETTER and GAMEPLAYATTRIBUTE_VALUE_INITTER.

Each OnRep_ body is one GAMEPLAYATTRIBUTE_REPNOTIFY(UMyHealthSet, Health, OldHealth) call, and every attribute needs a DOREPLIFETIME_CONDITION_NOTIFY(UMyHealthSet, Health, COND_None, REPNOTIFY_Always) line. The full .cpp with clamping is in gas-setup-patterns.md.

Hook	Fires	Use for
PreAttributeChange	Every current-value recompute	Clamping the current value only
PreAttributeBaseChange	Before a base-value write (const)	Clamping the base value
PostGameplayEffectExecute	After an instant GE, or one period of a periodic GE, writes the base value	Death, hit reactions, game events
PostAttributeChange	After a current value changed	Reacting to derived state

Registering and reading:

// Constructor of the ASC owner — the ASC finds subobject attribute sets automatically:
HealthSet = CreateDefaultSubobject<UMyHealthSet>(TEXT("HealthSet"));

// Runtime, authority only:
UMyHealthSet* NewSet = NewObject<UMyHealthSet>(this);
ASC->AddSpawnedAttribute(NewSet);

const float CurrentHealth = ASC->GetNumericAttribute(UMyHealthSet::GetHealthAttribute());

One ASC can host several UAttributeSet subclasses, but only one instance per class.

Tags in GAS

Tag definition (native tag macros, .ini tag sources), container matching and FGameplayTagQuery semantics belong to ue-gameplay-tags-messaging. What is GAS-specific:

// On the ability CDO (constructor): tags granted while the ability runs, and the gates.
ActivationOwnedTags.AddTag(CastingTag);
ActivationRequiredTags.AddTag(WeaponEquippedTag);
ActivationBlockedTags.AddTag(StunnedTag);
BlockAbilitiesWithTag.AddTag(MeleeTag);
CancelAbilitiesWithTag.AddTag(ChannelTag);

// On the ASC: query and react.
ASC->HasMatchingGameplayTag(StunnedTag);
const FGameplayTagContainer& Owned = ASC->GetOwnedGameplayTags();
ASC->RegisterGameplayTagEvent(StunnedTag, EGameplayTagEventType::NewOrRemoved)
    .AddUObject(this, &AMyCharacter::HandleStunnedTagChanged);

The callback is declared as void HandleStunnedTagChanged(const FGameplayTag Tag, int32 NewCount); and needs no UFUNCTION() — tag events are plain multicast delegates.

Loose tags are set directly instead of through a GE. The third argument chooses how the tag replicates:

ASC->AddLooseGameplayTag(StunnedTag);                                              // local only
ASC->AddLooseGameplayTag(BuffedTag, 1, EGameplayTagReplicationState::TagOnly);     // tag to all
ASC->AddLooseGameplayTag(BuffedTag, 1, EGameplayTagReplicationState::CountToOwner);// + count to owner
ASC->RemoveLooseGameplayTag(BuffedTag, 1, EGameplayTagReplicationState::TagOnly);
ASC->SetLooseGameplayTagCount(BuffedTag, 3, EGameplayTagReplicationState::TagAndCountToAll);

EGameplayTagReplicationState values: None, SimulatedTagOnly, TagOnly, CountToOwner, TagAndCountToAll. Anything other than None must be added on the server.

Gameplay Cues

Cues are cosmetic only. Tag prefix GameplayCue.; a GE triggers them through its GameplayCues array, or code fires them directly:

ASC->ExecuteGameplayCue(HitCueTag, ASC->MakeEffectContext());   // one-shot
ASC->AddGameplayCue(BuffCueTag);                                // persistent
ASC->RemoveGameplayCue(BuffCueTag);
const bool bActive = ASC->IsGameplayCueActive(BuffCueTag);

Class	Base	Override	Use
UGameplayCueNotify_Static	UObject	OnExecute_Implementation	Burst cue with no spawned actor
UGameplayCueNotify_Burst	UGameplayCueNotify_Static	data-driven burst effects	One-shot particles/sounds, no code
UGameplayCueNotify_HitImpact	UGameplayCueNotify_Static	data-driven impact effects	Surface-typed impacts
AGameplayCueNotify_Actor	AActor	OnActive_/WhileActive_/OnRemove_Implementation	Persistent cue needing an actor
AGameplayCueNotify_BurstLatent	AGameplayCueNotify_Actor	data-driven burst effects	Burst that must spawn an actor
AGameplayCueNotify_Looping	AGameplayCueNotify_Actor	data-driven looping effects	Looping auras and channels

// MyHitCue.h
#pragma once

#include "GameplayCueNotify_Static.h"
#include "MyHitCue.generated.h"

UCLASS()
class MYGAME_API UMyHitCue : public UGameplayCueNotify_Static
{
    GENERATED_BODY()

public:
    virtual bool OnExecute_Implementation(AActor* MyTarget,
        const FGameplayCueParameters& Parameters) const override;
};

UGameplayCueManager discovers cue assets under the scan paths configured in project settings.

Project Settings

GAS configuration is a UDeveloperSettings class: UGameplayAbilitiesDeveloperSettings (Project Settings → Gameplay Abilities). Read it with GetDefault<UGameplayAbilitiesDeveloperSettings>(). Notable fields: GameplayCueNotifyPaths, ReplicateActivationOwnedTags, bAllowGameplayModEvaluationChannels, plus the global curve/attribute tables. Runtime helpers stay on UAbilitySystemGlobals (GetGameplayCueNotifyPaths(), AddGameplayCueNotifyPath(), GetAttributeSetInitter()).

Deprecated — do not use

Do not emit	Use in 5.8	Source
AGameplayCueNotify_Static	UGameplayCueNotify_Static (a UObject)	Class never existed; GameplayCueNotify_Static.h:19
EGameplayModOp::Multiplicative	EGameplayModOp::MultiplyAdditive (legacy alias is spelled Multiplicitive)	GameplayEffectTypes.h:112-148
EGameplayModOp::Additive / Division	AddBase / DivideAdditive	Hidden back-compat aliases, GameplayEffectTypes.h:141-143
EGameplayAbilityInstancingPolicy::NonInstanced	InstancedPerActor	UE_DEPRECATED_FORGAME(5.5) in Abilities/GameplayAbilityTypes.h:46
UGameplayAbility::AbilityTags	GetAssetTags() / SetAssetTags()	UE_DEPRECATED_FORGAME(5.5) in Abilities/GameplayAbility.h:474
GetAbilitySystemComponentFromActorInfo_Checked()	GetAbilitySystemComponentFromActorInfo_Ensured()	UE_DEPRECATED(5.5) in Abilities/GameplayAbility.h:168
NetUpdateFrequency assignment on an actor	SetNetUpdateFrequency(100.f)	UE_DEPRECATED(5.5) in GameFramework/Actor.h:903
UGameplayEffect::StackingType (public read)	GetStackingType()	UE_DEPRECATED(5.7) in GameplayEffect.h:2407
UGameplayEffect::GrantedApplicationImmunityTags	UImmunityGameplayEffectComponent	UE_DEPRECATED(5.3) in GameplayEffect.h:2379
AddReplicatedLooseGameplayTag	AddLooseGameplayTag(Tag, Count, EGameplayTagReplicationState::CountToOwner) (the deprecation message's replacement; TagOnly if no client needs the count)	Function removed (no declaration in 5.8); the backing ReplicatedLooseTags member is UE_DEPRECATED(5.7) at AbilitySystemComponent.h:1941
FGameplayAbilitySpec::DynamicAbilityTags	GetDynamicSpecSourceTags()	UE_DEPRECATED(5.5) in GameplayAbilitySpec.h:242
UAbilitySystemBlueprintLibrary::MakeSpecHandle	MakeSpecHandleByClass	UE_DEPRECATED(5.5) in AbilitySystemBlueprintLibrary.h:249
UAbilitySystemGlobals config members	GetDefault<UGameplayAbilitiesDeveloperSettings>()	UE_DEPRECATED(5.5) throughout AbilitySystemGlobals.h
FGameplayEffectSpec::GetModifierMagnitude(ModifierIdx, bFactorInStackCount)	GetModifierMagnitude(int32 ModifierIdx)	UE_DEPRECATED(5.6) in GameplayEffect.h:1153
FActiveGameplayEffectHandle(int32), ResetGlobalHandleMap(), RemoveFromGlobalMap()	FActiveGameplayEffectHandle::GenerateNewHandle() or GetInstantExecutedHandle(); the global map is gone	UE_DEPRECATED(5.8) in ActiveGameplayEffectHandle.h:30,66,69

Common Mistakes

Implementing IAbilitySystemInterface only on the pawn: when the ASC lives on the PlayerState, the PlayerState must implement the interface too, otherwise UAbilitySystemBlueprintLibrary::GetAbilitySystemComponent fails on the owner.

Calling InitAbilityActorInfo only on the server: clients need it as well. Server path is PossessedBy, client path is OnRep_PlayerState. Without the client call, attribute change delegates never fire on the owning client.

Applying GEs before init: granting abilities or applying effects before InitAbilityActorInfo runs leaves the ASC without actor info and the attribute sets unregistered.

Clamping in the wrong hook: PreAttributeChange fires on every aggregator recompute, so it may only clamp NewValue. Death, hit reactions and gameplay events belong in PostGameplayEffectExecute, which only runs for executions (instant GEs and periodic ticks).

Forgetting CommitAbility: the ability runs, but no cost is paid and no cooldown starts.

Assuming loose tags replicate: AddLooseGameplayTag(Tag) defaults to EGameplayTagReplicationState::None. Pass TagOnly or CountToOwner from the server, or grant the tag through a GE.

Stacks silently capped: applications beyond GetStackLimitCount() are rejected without an error. Check GetCurrentStackCount(Handle) before assuming a stack landed.

Startup effects in BeginPlay without an authority check: late joiners re-apply them. Gate every GiveAbility and startup GE behind HasAuthority().

AI with no PlayerState: put the ASC on the AI character, call InitAbilityActorInfo(this, this) and set Minimal replication.

Related Skills

• ue-gameplay-tags-messaging — tag definition (native tag macros, ini tag sources), containers, FGameplayTagQuery and gameplay messaging
• ue-networking-replication — DOREPLIFETIME variants, RPCs, prediction keys, push model
• ue-animation-system — montage assets, notifies and slots that the montage ability tasks drive
• ue-character-movement — movement modes that root-motion ability tasks manipulate
• ue-cpp-foundations — UPROPERTY/UFUNCTION specifiers, delegates, TSubclassOf, subsystems
• ue-data-assets-tables — UCurveTable and UDataTable assets behind attribute initialisation and FScalableFloat
• ue-state-trees — running abilities from State Tree tasks
• ue-actor-component-architecture — component creation, subobject registration, replication of subobjects
• ue-gameplay-framework — PlayerState and Pawn lifecycle, and damage without GAS (TakeDamage, UDamageType)
• ue-input-system — Enhanced Input actions bound to ability input ids
• ue-game-features — granting abilities and attribute sets from a game feature plugin
• ue-niagara-effects — Niagara systems, user parameters, data interfaces and data channels
• ue-ui-umg-slate — UMG widgets, Slate, Common UI and MVVM