A buff is just an effect that introduces a temporary, permanent, or recurring change to a game unit's attributes from its AttributeSet. Buffs can either be good or bad, supplying either bonuses or penalties. For example, you might have a hex buff that slows a unit to half speed, an angel wing buff that increases unit speed by 2x, or a cherub buff that recovers 5 hp every 5 seconds for 3 minutes. A GameplayEffect affects an individual gameplay attribute in the UAttributeSet that's attached to an AbilitySystemComponent of an Actor.
GameplayAbilities API – implementing buffs with GameplayEffect
Getting ready
Brainstorm your game units' effects that happen during the game. Be sure that you've created...