The character having some sort of crazy-ass electromagnetic ability (that I cannot honestly be bothered to think too much about) that is able to alter the density of objects. By causing molecules to spread further apart, the object would take longer to heat up (or the reverse). This would cause the object's traits to alter though. It could also explain the levitation: the object could be made less dense, and the air beneath it more dense, therefore causing it to float (like a beach-ball in water). I've probably got this completely wrong, but it might be something to go on xP