Ghostrick Stein (SHSP-EN021) - Shadow Specters Unlimited

Cannot be Normal Summoned, unless you control a "Ghostrick" monster. Once per turn: You can change this card to face-down Defense Position. When this card inflicts battle damage to your opponent: You can add 1 "Ghostrick" Spell/Trap Card from your Deck to your hand. You can only use this effect of "Ghostrick Stein" once per turn.