Are the tokens black? If so, that's one heck of an engine support card. If not, their type shouldn't be Zombie as all Zombie tokens printed so far have been black.

In addition to the lack of a token color, I like how is being used as a verb.

What about whenever you sacrifice a non-Zombie creature? Still flavorful, but if color matters it won't be appropriate. In that case, nontoken black creature.

Hmm. I could see the problem of this being repeatable with the tokens being problematic, but the cost hopefully balances that out since you're paying for a Grizzly Bears with each sacrifice, and the black means you at least need to be genning a high amount of black mana (so you're either loaded up on swamps or can untap some kind of lotus or Den of Whispers). Color was only included to limit the power of the card and keep it at the uncommon level, weakening it for draft play. Non-zombie definitely is flavorful, but aside from shapeshifters for immediate flavor purposes this set has no interest in tribal, where I fear non-Zombie clause also pushes the card.