Advanced format ruling
Horus the Black Flame Dragon LV4
Card effect (current official text)Control of this face-up card cannot switch. During the End Phase, if this card destroyed a monster by battle this turn: You can send this face-up card to the Graveyard; Special Summon 1 "Horus the Black Flame Dragon LV6" from your hand or Deck.
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.