Demonic powers. Preferably wolf demon ice elemental.
Seems like you'd get ripped off. WEAKSAUCE
Then I could just kill the dude I sold my soul to and get it back. Unless the deal is with a crossroads demon like in supernatural, then I would get to fight Hellhounds and that would kick ass!
thats a hard one ,, i think it would be for the exchange of the safety of the girl i love if she was in a life death situation. .. i heard somwere if u sold ur soul for a noble cause , u get to keep it ,,, but it has to be something really really noble , , not peace on earth and that shit ,,
but if u sell it for personnal pleasure ,, think is it worth it eternal damnation ,, an eternity of fire and suffering .. of course NOT