Karthus the Deathsinger

+2: Create a unblockable 1/1 black mist token and if there are more than four on the field, sacrifice them and gain control of target creature
+3: Return target card from your graveyard to your hand or return target card from exile to your graveyard
-16: Deal 7 damage to all enemy creatures and planeswalkers, then gain life equal to the amount of cards in all enemy graveyards