Koa'ki Meiru Wall (BP03-EN081) [Battle Pack 3: Monster League]

During each of your End Phases, destroy this card unless you send 1 Iron Core of Koa'ki Meiru from your hand to the Graveyard or reveal 1 Rock-Type monster in your hand. You can Tribute this card to negate the activation of an opponent's Spell Card and destroy that card.