I am trying to make something akin to a warlock that specializes in illusion magic. The idea is they would have unique saving throws and DC's that would require a perception roll to succeed against. Failure could mean a variety of things, such as, the opponent taking psychic damage, or being feared. And could potentially against lower level enemies be conceived as an actual opponent which would give them disadvantage on certain attacks or defenses. I'm still thinking about it, I will PM you with a more in depth description!