Seagraf Shamblers

Zombie Offering (You may cast this spell as though
it had flash by sacrificing a Zombie and paying the difference in mana costs between this and the sacrificed
Zombie. Mana cost includes color.)
You may cast this spell from your graveyard as
long another creature died this turn.
Seagraf Shamblers enters the battlefield tapped
with a +1/+1 counter on it for each creature card
in your graveyard.