Gameplay Effects Deep Dive¶

Gameplay Effects (GEs) are the workhorse of GAS. They are the data-driven bundles that actually do things to actors: heal them, burn them, speed them up, slow them down, grant them abilities, make them immune to crowd control. If Gameplay Abilities are the verbs, Gameplay Effects are the nouns — the tangible changes applied to an actor's state.

This section goes deep. If you are looking for a high-level overview, start with the Core Concepts: Gameplay Effects Overview first, then come back here.

The Three Duration Types (Quick Recap)¶

Every Gameplay Effect has a Duration Policy that determines its lifetime:

Duration and Infinite effects are added to the Active Gameplay Effects Container. Instant effects are executed — they modify the base value of an attribute and are gone. This distinction matters a lot, and we cover it thoroughly in Duration and Lifecycle.

Decision Tree: Where Should I Go?¶

Not sure which page answers your question? Start here.

"I want to..."

• ...understand how GEs are created, live, and die — Duration and Lifecycle
• ...add or multiply an attribute by some value — Modifiers
• ...figure out how a modifier gets its number — Magnitude Calculations
• ...write a complex formula that touches multiple attributes — Execution Calculations
• ...make a buff that stacks up to 5 times — Stacking
• ...grant abilities, apply tags, or block other effects — GE Components
• ...control when effects can apply based on tags — Tags and Requirements
• ...make my character immune to fire damage — Immunity
• ...implement cooldowns or resource costs for abilities — Cooldowns and Costs
• ...pass a damage number from code into an effect — SetByCaller
• ...create or modify effects at runtime in C++ — Dynamic Effects

Suggested Reading Order¶

If you are working through this for the first time, this order builds concepts progressively:

1. Duration and Lifecycle — the foundation
2. Modifiers — how attributes get changed
3. Magnitude Calculations — where the numbers come from
4. SetByCaller — the most common way to pass data into effects
5. Execution Calculations — the power tool for complex formulas
6. Stacking — what happens when the same effect is applied twice
7. GE Components — the modular architecture (5.3+)
8. Tags and Requirements — conditional application and ongoing requirements
9. Immunity — blocking effects
10. Cooldowns and Costs — the ability economy
11. Dynamic Effects — runtime creation and modification

Key Source Files¶

For engine spelunkers, the relevant headers live under Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/: