When this card is activated: You can add 1 "K9" monster from your Deck to your hand. "K9" monsters you control gain 900 ATK during any turn in which your opponent has activated a monster effect in the hand or GY. If this card in the Spell & Trap Zone is destroyed by card effect: You can Set 1 "K9" Quick-Play Spell from your Deck or GY. You can only use this effect of ""A Case for K9"" once per turn. You can only activate 1 ""A Case for K9"" per turn.