It's something to do with the way mp and dots/hp ticks are calculated. One is server side and one is player side. What's happening is your mp is refreshing twice instead of just the once causing the pm to drain (one refresh) then build up to what it should be (2nd refresh) the problem comes likes many of you have rightly said when you think you have enough mp to dark arts and then that 1st refresh comes in and removes enough mp to stop the ability firing off. Completely throwing you off your game. Or when you do run low of pm and it ticks off dark side. The mp mechanic is exactly as it should be but instead of 2 refreshes there should be only the last one. Give them time, they will fix it. They acknowledged it, but nothing comes instantly. It's still in my eyes a great class, that just needs a little more tlc.