Koa'ki Meiru Overload

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. During either player's turn, when your opponent would Summon a monster(s): You can Tribute this card; negate the Summon, and if you do, destroy that monster(s).