The Eldritch Engine

{t}: Add X {b} to your mana pool, where X is the
number of creature cards in your graveyard.
At the beginning of your upkeep, if you control a creature called The Lord of Skulls, each
opponent must sacrifice a creature. You gain life
equal to the number of creatures sacrificed this
way.
If a player can't sacrifice a creature, they lose the
game.