REDU format ruling
Kuriboh

Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)During damage calculation, if your opponent's monster attacks (Quick Effect): You can discard this card; you take no battle damage from that battle.
Rulings
- Kuriboh does not target the attacking monster.
- Kuriboh only prevents Battle Damage to your Life Points; it will not prevent your monsters from being destroyed.
- Kuriboh can only be activated while in your hand, its effect cannot be used while Kuriboh is on the field.
- Kuriboh's effect is a Quick Effect.
- Kuriboh is activated during damage calculation. If your opponent attacks with Injection Fairy Lily and activates her effect, you can chain Kuriboh to reduce the damage to zero.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.