REDU format ruling
Dark Horus
Nearest-era rulings (Tengu, Sept 2011) — no REDU-specific archive exists.
Card effect (current official text)Once per turn, after resolving a Spell Card that was activated during your opponent's Main Phase: You can target 1 Level 4 DARK monster in your Graveyard; Special Summon that target. This card must be face-up on the field to activate and to resolve this effect.
Rulings
(1) Once per turn, when a Spell Card is activated during your opponent's Main Phase, you can Special Summon 1 Level 4 DARK monster from your GY.
- The (1) optional Trigger Effect activates AFTER a Spell Card's activation resolved (starting a new chain).
- This effect CAN miss the timing if Chain Link 1 was NOT the activation of a Spell Card.
- This effect WILL NOT trigger in response to the effect of face-up Spell Card (ex: Black Garden).
- This effect WILL NOT trigger if Dark Horus is flipped face-down before it can activate its effect.
- This effect WILL NOT resolve if Dark Horus is flipped face-down before resolving its effect.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the REDU forum — sourced change requests get reviewed.