Koa'ki Meiru Guardian (SESL-EN048) - Secret Slayers 1st Edition

During each of your End Phases, destroy this card unless you send 1 "Iron Core of Koa'ki Meiru" from your hand to the GY or reveal 1 Rock monster in your hand. During either player's turn, when a monster effect is activated: You can Tribute this card; negate the activation, and if you do, destroy that monster.