Sliv and Lilith

+2: Each opponent sacrifices a creature. You put a 1/1 colorless sliver creature token onto the battlefield for each creature sacrificed this way.
-3: Look at the top six cards of your library. Put all slivers revealed this way onto the battlefield, exile the rest.
-12: Sliv and Lilith replaces your commander permanently. Deal 20 damage to each opponent. This damage cannot be prevented or redirected.