Koa'ki Meiru

Koa'ki Meiru, sometimes romanized as Core Chimail (a combination of the words "Core", "Chimera", and "Mail", a synonym for armor) are a series of monsters from Raging Battle and Ancient Prophecy.

Most effects of these cards are targeted to send "Iron Core of Koa'ki Meiru "or revealing a card in your hand (Except for "Koa'ki Meiru Valafar" who doesn't give a revealing option). Also, if the controller doesn't send or reveal any card from the above, that Koa'ki Meiru is destroyed.

All of the "Koa'ki Meiru" have the same mark on some part of their body or on a weapon they have.

Playing Style
The main strategy of the "Koa'ki Meiru" is Anti-Meta - A Deck build which oppose the popular Decks that are played. For example, "Koa'ki Meiru Drago's" effect was designed especially to oppose "Lightsworn, Dark Armed Return, and "Blackwing" Decks for their Swarming capabilities. In addition, several low-level Koa'ki Meiru monsters have ATKs that are considered extraordinarily high for a monster of it's level (there are 4 monsters with 1900 ATK and 2 monsters with 2000 or more ATK, all at level 4), as well as having a beneficial effect (if not counting the revealing part), thus they can play semi-beatdown as well.

An effective way to utilize their capabilities without having to discard a "Iron Core of Koa'ki Meiru" every round, is to place a second copy of each "Koa'ki Meiru" monster you utilize. Since each of the weaker "Koa'ki Meiru's" merely requires you to reveal a monster of their Type simply revealing the same monster turn after turn will make you capable of continuous use of your "Koa'ki Meiru" monsters on the field. The Monsters' same-Type support was designed to make them splashable into many decks, essentially to put the Meta at full risk.

Weaknesses
Because Iron Core of Koa'ki Meiru may often be in the graveyard, it is vulnerable to cards that can remove it from play, such as Gladiator Beast Retiari, and Macro Cosmos. Also, having multiple Koa'ki Meiru monsters on the field at once can be extremely dangerous, as each one would require you to reveal or discard a card from your hand at the End Phase; leaving hand and field advantage very hard to maintain, unless multiple copies are used (for example, 3 Koa'ki Meiru Powerhands only require 1 Normal Trap Card revealed). Another weakness this deck seems to have is Mind Crush, D.D. Designator, etc. Because of the constant hand revealing, your hand is vulnerable to cards that target cards in your hand.

Furthermore, the fact that using all of them in one deck can lead to a lot of inconsistency, as well as their over reliance on a card that provides no meaningful advantage whatsoever, Koa'ki Meiru's are best used as splashable tech, such as Drago in a Dragon Deck and Doom in a Fiend Deck.

Amazingly, one way to beat the Koa'ki Meiru format is to have the opponent permanently reveal their hand to you on their turns in order to make them either discard an Iron Core of Koa'ki Meiru or destroy the card, since they cannot "reveal" the card to you. Such cards include Respect Play and Ceremonial Bell.