The ability to eat other people's talent. I wouldn't gain the talent, but they would lose it forever. This includes powers. Once again I provide the dick move answer for a thread.
If that seems a bit too overpowered (or is too much of a dick move), then I change my answer to this:
If I'm talking to someone and they tell me a lie then they are forced to insantly yell out the following phrase "I want to take the ears off, but I can't. I hop, and when I hop, I never get off the ground. It's my curse, my eternal curse! I want to take the ears off but I can't! It's my curse! It's my fucking curse! I want to take the ears off! Please! Take them off! Please!" - No, you don't get a cookie for naming the reference, because by now everyone should know it. If you don't, shame on you.