REDU format ruling
Gravekeeper's Vassal

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Any battle damage this card inflicts to your opponent is treated as effect damage instead.
Rulings
- The damage that is inflicted to your opponent’s Life Points as a result of battle with Gravekeeper’s Vassal attack is treated as effect damage instead, not Battle Damage. So your opponent cannot use Kuriboh or Waboku to prevent the damage, for example.
- A monster destroyed by Gravekeeper’s Vassal in battle is still treated as destroyed as a result of battle (for Mystic Tomato, Nimble Momonga, etc.).
- If you equip Fairy Meteor Crush to Gravekeeper’s Vassal, and attack a Defense Position monster and inflict Battle Damage to the opponent’s Life Points, the damage is treated as effect damage due to Gravekeeper’s Vassal’s effect.
- You cannot activate Barrel Behind the Door against damage inflicted by Gravekeeper’s Vassal because its effect is a Continuous Effect and you cannot activate Barrel Behind the Door against Continuous Effects.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.