Ability Effect

Ability Effect is blueprint being spawned as an effect of the ability.
It can be any actor, such as fireball projectile, summoned item, buff, magic rune spawned on the ground.

There are few predefined ability effect actors that can be used in Abilities.

However not all Abilities are using ability effects, when effect is simple enough, then there is no need to spawn separate actor for it, and then effect logic is defined directly in Ability blueprint.
Example of that could be healing abilities.

Usage example of damage sphere ability effect spawned by Inferno ability.

It spawns sphere checking if there are any enemy actors inside and applies damage to them.
Packaging this logic into separate actor allows us to reuse it in multiple Abilities.