[Snake]

'PvP based' sounds more like a Gold thing, in my opinion. Due to you know, Law's End and stuff. But if we are going for thematic Arenas. It should be the least like this:

Sigrogana: PvE challenges only with teamplay in mind, due to the IC way the Empire 'enjoys' seeing needless violence against humans/similar. So nothing changes when the Arena is active in it's main place.

Kysei: PvE challenges with survival theme, with a little of PvP challenges and rankings based on chess puns, that could be better viewed in a 'sport' or 'game'-ish way, ICly.

Lordwain: PvP/PvE challenges under an intense field hazard, or limited resources, such as skills and spells eating away twice as much FP, and same goes to durability, while all parties are suffering a rather crippling frostbite or burn.

Alstalsia: Honored PvP fights, in which all the matches should be balanced around the fighter's playstyle. So people who use basic hits will only be allowed to fight other basic hit users, while magicians will only fight other magicians in a 'fair' fight.

Gold: Mass PvP in a free for all style, no rules but Tarson's 'no-killing rule'. In a place that doesn't quite have good ears for it.