Dragon Graveyard

Sacrifice a creature, Add {b}{b}{g}{g}.
Whenever a creature with a -1/-1 counter on it dies you gain 1 life.
Once per turn you may cast Tattered Rider, Armored Skullwinder, Grieving Reaver, City Plauger, or Blaivken, Plague Bearer from outside the game. You may only control one of each at a time.