[TSHD-EN087] Core Overclock

All face-up "Koa'ki Meiru" monsters you control gain 500 ATK. Once per turn, during your Main Phase, you can discard 1 "Iron Core of Koa'ki Meiru" to have all face-up "Koa'ki Meiru" monsters you control gain 1000 ATK, until the End Phase.