Factions maybe.... Sorry if this is a bit warcraftish

Humans, Dwarves, Elves are Faction A

Orcs, Trolls, Kolbolds are Faction B

Or pretty races vs ugly races. (Also, remember Kolbolds are now officially lizard people.) You can add more if you wish.

Though I'd probably not be very fair in this. I'm that DnD mage that you hate to RP against because I make every other roll of yours a death roll when I'm lvl 1 and your lvl 50+ :P. yay for the (Now fixed) Golden bug combo!

If I did join this, I'd probably be better off as a neutral party or something, that way I wont get in positions where Its me vs another person very often. :P. I dunno, I'd need to see some very specific rules against what can and can't be done. I've got a looot of lethal combos with one or two spells that seem harmless by themselves.

Also shapshifting/illusions would prob be the norm.

militaristic hogwards might be terrible or good depending on how you handle it.