Koa'ki Meiru Overload (SESL-EN051) [Secret Slayers]

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. When your opponent would Summon a monster(s) (Quick Effect): You can Tribute this card; negate the Summon, and if you do, destroy that monster(s).