Gem-Knight Sardonyx (HA07-EN001) - Hidden Arsenal 7: Knight of Stars Unlimited

This card is treated as a Normal Monster while face-up on the field or in the Graveyard. While this card is face-up on the field, you can Normal Summon it to have it become an Effect Monster with this effect. // * When this card destroys an opponent's monster by battle and sends it to the Graveyard: You can add 1 "Gem-Knight" card from your Deck to your hand.