An arena? That depends on what you mean by it. Like a Colosseum or a simple make-shift ring that could just be in the Town Square for brawls. I don't think the city fortress is big enough to have a Colosseum one. But if we did decide to do that, I can only think they'd be like Rome and toss Mutant prisoners in the ring to be slain by Cat warriors. But ugh, this makes the RP feel like Gladiator. -_-