Would be nice if when playing with more than 2 teams the mini-map displayed each teams colour, opposed to all enemies red. Likewise turn order probably needs a coloured frame for each portrait as it's kinda difficult to see who's turn is next.
The preset classes are alright. But custom character builds really need to be implemented to allow players more versatility. Also on versatility would it not be nice on maps if barrels type or surfaces type on round start were randomised, so players cannot 'learn' a map as well.
By default the chat is also hidden once battle starts, probably should not be.
Also the teleport and nether-swap are far too cost effective at 1 AP for what you can do with them. Probably should cost 2-3 AP or have a higher cool-down for the arena mode.