Xlflck, Sliver Leviathan

+2: Slivers you control get your choice of Deathtouch, Double Strike, Flying, Haste, Lifelink, Trample, Infect, Fear, or Vigilance until end of turn.
-3: Create five 1/1 sliver tokens with haste.
-12: Create X 1/1 Sliver tokens with haste where X is double the number of slivers on the battlefield. Untap all slivers.