Can Be Applied
To specify whether character can get an effect or not, it should implement interface I_CanGetEffect.
This interface has 1 function CanEffectBeApplied.
Let's take a look at implementation of this function in BP_BaseAI.
When any actor tries to apply effect to AI, firstly it checks whether it can be applied through this function, if it returns true, effect will be applied, otherwise it won’t.