Add 1 "Koa'ki Meiru" card from your Deck to your hand, except "Diamond Core of Koa'ki Meiru". You can banish this card from your Graveyard; for the rest of this turn, "Koa'ki Meiru" monsters you control cannot be destroyed.
When Koa’ki Meiru Crusader destroys a monster by battle he can retrieve a Koa’ki Meiru card from your graveyard. Use this to retrieve Diamond Core of Koa’ki Meiru for more searches.
Iron Core of Koa’ki Meiru
Iron Core of Koa’ki Meiru is the key card of many Koa’ki Meiru decks so search it out with Diamond Core of Koa’ki Meiru. And with Iron Core of Koa’ki Meiru in your hand you will have access to support like Iron Core Luster and Iron Core Specimen Lab.
You can't ruin something that, by its very definition, is broken. Anything that can shake things up even for a little while is always welcome, unless you're satisfied dueling against the same 3 or 4 decks in PvP that is.