Iron Cage (BLRR-EN012) [Battles of Legend: Relentless Revenge]

When this card is activated: Send 1 monster you control to the GY, or, if "Golden Castle of Stromberg" is in the Field Zone, you can send 1 monster your opponent controls to the GY, instead. Once per turn, during your Standby Phase: You can target 1 monster in the GY that was sent there by this card's effect; destroy this card, and if you do, Special Summon that monster to your field. You can only activate 1 "Iron Cage" per turn.