Should Monsters have Mana Bars?
In D2, some monsters had the annoying habit of draining your mana. Why not WE return the favour in D3? Monsters could have mana bars and we could use attacks like mana burn(not 100%) against them. These wouldn't be of too much use against melees, but against casters it could be deadly. Even if people think that the ability of being able to drain your enemies mana is too easy, we could atleast see when they have enough mana to cast their attacks.
In PvP, the abilities uses are simple enough.
Maybe this shouldn't be a skill for any class, but perhaps a very rare mod on some items.