REDU format ruling
Light and Darkness Dragon
Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Cannot be Special Summoned. While face-up on the field, this card is also DARK-Attribute. Once per Chain, during either player's turn, when a Spell Card, Trap Card, or monster effect is activated: This card loses exactly 500 ATK and DEF and that activation is negated. When this card is destroyed and sent to the Graveyard: Target 1 monster in your Graveyard (if possible); destroy all cards you control, also Special Summon that monster (if any).
Rulings
- For the mandatory ② effect to resolve, this card must be able to both negate the activation and also lose exactly 500 ATK and 500 DEF. If you can’t do either, you do neither.
- Vs Spirit Monsters, Lyla, Treeborn Frog, Vayu, etc: These trigger effects will be negated by this card’s ② effect, and can then trigger again. (This can "loop" until Light and Darkness Dragon can’t lose any more ATK/DEF.)
- The ③ effect can cause effects, to have incorrect activation timing.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.