imo there should be an Assassin/anti-mage class. They could steal mana, have an ability where they can temporarily move faster, do high damage when attacking from behind, be able to nuke a single target but no mob control whatsoever, and so on. They would have to be melee so that they don't just annihilate all else in PvP, or at least have less range than archers and mages. Also, they would have to be made so that they require substantial support. This could probably be a human class.