I like what the Marquis of Death did to Doctor Doom making him think he won and had lived a nice life only to find out a few seconds had passed in reality.
The Joker is probably my favorite villain tho he does it all the time. Everything he does to Batman is to try break him mentally.
Batman is also arguably one to play mind games. I mean he's literally a symbol of fear for criminals not just in Gotham. He doesn't even have to do something at times his mere presence is enough to just say nope and dip. If that isn't messing withing someone mentally then idk what is.
Scarecrow would also work with his fear toxins.
What’s wrong, scared? - YouTube this kinda works for both Batman and Scarecrow its Scarecrows toxin but it essentially forces the victim to see their worst fear and Scarecrow see's Batman not some eldritch being that breaks your mind he sees Batman.
