Gravecrawler

Sacrifice a Human: Transform this creature. Activate only as a sorcery.

Return all Zombie creature cards from your graveyard to the battlefield tapped, then destroy all Humans.

At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Haste Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)