Ha ha ha! I'll buy that. But it can't be gladiatorial battles every time. The monster needs to have a little back story and a lair (the bonus there is that you can make up your own monsters and not be limited to folklore). And then you could sometimes have guest warriors help take down the particularly nasty ones.

Maybe one monster is dragged into the arena, but the next has to be lured out of its cave to fight in an open field. Another has to be gone after in its underground labyrinth. A werewolf might be disguised among guests at a party and have to be discovered and fought in the virtual mansion. A ruins, a factory, inside a car, under water—the possibilities are endless. Maybe he has to fight a minotaur in a china shop!

Oh, and the monster has to win sometimes. Rematch!