REDU format ruling
Zombie Mammoth

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Destroy this card if you do not have a Zombie-Type monster in your Graveyard. When this face-up card is destroyed, inflict damage to its controller equal to its original ATK.
Rulings
- If Zombie Mammoth is attacked while face-down and its controller does not have any Zombie-Type monsters in their GY, Zombie Mammoth is destroyed by its effect after damage calculation.
- If it is destroyed by the battle, its effect is not applied.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.