Erthenia

I got a bit stuck there. First, I miscalculated the bonus damage from the strength modifier. Now I'll simulate the turns, although I doubt anything will change significantly.

What if I enter the arena with the beheading ability, will it also not kill the opponent?

Why not? Of course, it will. No one forbids using spells/killing abilities. But if the opponent dies, you won't be able to get away with just a simple apology.