Tengu format ruling
Delta Crow - Anti Reverse
Card effect (current official text)If you control a "Blackwing" monster: Destroy all face-down Spells and Traps your opponent controls. If you control exactly 3 "Blackwing" monsters, you can activate this card from your hand.
Rulings
- You cannot activate "Delta Crow – Anti Reverse" from your hand if you control 4 or 5 "Blackwing" monsters.
- If you control exactly 3 "Blackwing" monsters, you can activate "Delta Crow – Anti Reverse" from your hand during your turn or during your opponent’s turn.
- The number of "Blackwing" monsters on the field is only an activation requirement. If the number of Blackwings is no longer correct when "Delta Crow – Anti Reverse" resolves, its effect is still applied. "Delta Crow – Anti Reverse" only destroys face-down Spell and Trap Cards. If those cards are chained in response, they are not destroyed.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Tengu forum — sourced change requests get reviewed.