Darkness

+3: Gain control of target creature. That creature gains haste and fear until end of turn. Return creature back to the owner at your end step.
-3: Gain control of any creature. You have that creature, unless that player pays life according to its mana value.
-X: Destroy X creatures and gain X life. If X is more than 5, make this a 6/6 token creature with Shroud, Vigilance and Trample until end of turn.