Ok, you've just been tossed inside of a nuclear reactor, but you've survived. Not only have you survived this terrible ordeal, but you've been granted amazing super powers! Just one problem, the power you have is either completely useless, incomplete, or does more harm than it ever will good. What's your super power?
The ability to burst into flames, like the human torch. But with no resistance to flames or heat, so you just burn to death once you activate your powers.
The ability to turn into liquid. But it's just regular, non-sentient liqud, and doing it basically kills you.