You see, a fight to the death wouldn't work here, as some characters won't die, or keep coming back.
So it goes beyond death, the one who preservers and is just too thick headed to beat (not to kill).
I can definitely see Kratos taking the cake, he would just drop them in lava and chain them inside hell for eternal torment.
Nothing is too brutal for him, and that means he can brawl without hesitation.
So what does it take to beat Kratos, you can't kill him?
Well, probably the same, chain him for eternity or dismemberment.
The only character that i can fathom being capable of such atrocities is Kratos obviously.