Your search for "Zombie Mammoth CSOC-EN030" revealed the following:
Zombie Mammoth - CSOC-EN030 - Common - Unlimited from Crossroads of Chaos Unlimited, available at 401 Games Canada. Rarity: Common Card Text:Destroy this card if you do not have a Zombie-Type monster in your Graveyard. When this face-up card is...
Zombie Mammoth - CSOC-EN030 - Common - 1st Edition from Crossroads of Chaos 1st Edition, available at 401 Games Canada. Rarity: Common Card Text:Destroy this card if you do not have a Zombie-Type monster in your Graveyard. When this face-up...