Advanced format ruling
Horus the Black Flame Dragon LV8
Card effect (current official text)Cannot be Normal Summoned/Set. Must be Special Summoned by "Horus the Black Flame Dragon LV6", and cannot be Special Summoned by other ways. During either player's turn, when a Spell Card is activated: You can negate the activation, and if you do, destroy it. You must control this face-up card to activate and to resolve this effect.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.