Skies Above Vat

At the beginning of your upkeep, sacrifice Skies
Above Vat unless you sacrifice a creature.
Whenever you sacrifice a creature each opponent
loses 2 life.
When Skies Above Vat is put into a graveyard
from the battlefield create two 1/1 black Shade creature tokens.They have "{b}: this creature gets
+1/+1 until end of turn."