I've actually recently been writing down some special powers for my characters and here are a few interesting ones I came up with.
The ability to turn anything it touched into a bomb.
Placing a restriction on the opponent's power (E.I. can't use a certain ability, or can't go above a certain level, etc.) and if they break those restriction, they get hurt.
Placing a chain of sorts on your opponent that causes any damage, physical, mental, or emotional, that is dealt to one to go to the other as well.
The ability to reflect all attacks that you know are coming with twice the force, but only ones you know are coming and can react to.
Memory manipulation: The ability to place memories in an opponent's mind or scramble their thoughts for a bit to make them think that they're someone else.
And those are some of my ideas for powers. What do you think?