Conquerer of Three Worlds Ragnaraku (EB01-039) - Extra Booster: Memorial Collection Foil

[Main] DON!! -1 (You may return the specified number of DON!! cards from your field to your DON!! deck.): K.O. up to 1 of your opponent's Characters with a cost of 8 or less.
[Trigger] Ad up to 1 DON!! card from your DON!! deck and set it as active.