No, not the Cenobite! He's a member of the initiative.
Yea, he was initially going by Bolder but Taskmaster changed it to Butterball he was a fat kid and to motivate him to try harder.
His power is he can't be hurt. Period. Not even telepathy, mental powers can nudge him but he's immune to outright mental attack.
He doesn't need to breath. He doesn't need to eat (he does anyway and they figured, *eventually*, enough starvation might allow him to lose some weight). He doesn't get tired- he can keep running at his (slow, out of shape) rate forever. He might need to sleep but as nothing can hurt him it's not like you could keep him awake on purpose. His fellow (powered) students one tried to haze him by attacking him in his sleep. He slept through it.
Butterball was eventually let go because although he couldn't be hurt, nor could they make him into an effective hero (his power meant he gained no benefit from exercise, his muscle mass was set), so you have an utterly unhurtable person who was well below average in a fight.
Dude Juggernaut can just punch him so hard he buries him under the pavement under several tons of debris.
Butterball has NO other superhuman powers and his other stats are actually BELOW normal human. He'd never dig himself out. Trapped underneath several tons of material with no way out, unable to move, and in total darkness..........forever! I'd rather be dead.
Man, the more you think about it, the more it sounds like this kid's powers are actually a curse. So many ways you can screw him over and get away with it, he'd be a sadist's dream come true.
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..even the outer hells are indifferent matters for they bow only to potent and archaic Nodens.