Malefic grasp deals damage and causes the dots on it's target to tick 100% faster. It's kind of like haunt and shadow embrace (which will be gone in MoP), but malefic grasp causes your dots to do 100% more dps while SE and haunt causes your dots to do 35% more dps. And your dots will obviously be balanced around malefic grasp, so your dots will do about 50% less damage than they do now... They wouldn't have to nerf your dots if malefic grasp itself did no damage at all, but it looks like it will do about the same dps as shadow bolt. so multi doting is pretty much a waste of time in MoP.