Koa ' ki Meiru " Koa ' ki Meiru " , Japanese for " Core Chimail " ( コアキメイル " Koakimeiru " ) , a combination of the words " Core " , " Chimera " and " Mail " ) , sometimes romanized as " Core Chimair " ( a combination of the words " Core " and " Chimera , " ) is an archetype of cards primary from " Raging Battle " , " Ancient Prophecy " , " Stardust Overdrive " , " Absolute Powerforce " and " The Shining Darkness " . This archetype received more Anti - Meta and support cards in later sets " Starstrike Blast " , " Primal Origin " and " Secrets of Eternity " . The majority of their effects center around manipulating the " Iron Core of Koa ' ki Meiru " or reveal ing one in your hand to activate an effect . Almost all of the monsters require a maintenance cost in the form of sending an Iron Core to the Graveyard or revealing a monster of the same type . There are exceptions , such as that of " Koa ' ki Meiru Powerhand " , where you must reveal a Normal Trap Card , or " Koa ' ki Meiru Valafar " where you have to send an " Iron Core of Koa ' Ki Meiru " and cannot reveal any card in your hand instead . Another is " Koa ' ki Meiru Ice " , where a Continuous Spell Card is revealed . " Koa ' ki Meiru " are all EARTH , WIND , WATER or FIRE Attribute monsters , rendering them immune to their own control - based effects , which often affect LIGHT and DARK monsters . All of the " Koa ' ki Meiru " have the same mark ( 3 dragons ) on some part of their body or on a weapon they have . Also , many " Koa ' ki Meiru " and related cards ' artwork uses yellow , orange , and red , except for " Koa ' ki Meiru Ghoulungulate " . According to " Iron Core Specimen Lab " , " Kozaky " and " Magical Scientist " experimented and created the " Koa ' ki Meiru " Monsters . Playing Style . The theme was initially designed to bring down the dominating Decks of over 2 banlists and therefore centered around heavy control elements . Seeing as the meta was " completely " dominated by LIGHT and DARK Decks , effects specifically targeted both Attributes therefore bringing about a specific " Meta " , " Anti - Meta " theme . Because of their high ATK , 11 Level 4 monsters from 1900 ATK , topping out at 3000 ( " Koa ' ki Meiru Valafar " and " Koa ' ki Meiru Maximus " ) , and the nature of the new support , the theme has taken a more aggressive approach with powerful beatdown elements , namely " Koa ' ki Meiru Rooklord " and " Koa ' ki Meiru Urnight " . Generally speaking , there are two ways to use " Koa ' ki Meiru " cards . The most obvious is simply to use a dedicated Deck ; the other way is to use individual the " Koa ' ki Meiru " monsters as a supplement to Type specific Decks of their type , giving an " Anti - Meta " controlling aspect to it as well as being able to maintain it through the alternative maintenance cost ; for example , using " Koa ' ki Meiru Drago " in a Dragon - Type Deck as seen in " Disaster Dragon " builds . In order to run a dedicated " Koa ' ki Meiru " Deck , no matter the style , you ' ll need multiple ways to retrieve the " Iron Core of Koa ' ki Meiru " from your Deck and Graveyard . Good cards for this include " Koa ' ki Meiru Boulder " , " Koa ' ki Meiru Crusader " , " Diamond Core of Koa ' ki Meiru " , and " Core Transport Unit " . " Iron Core Immediate Disposal " is also nice mid game after building up resources in your hand . Cards that help thin the deck or dump the " Core " into the Graveyard help make the deck faster and more consistent . You must also be wary of keeping more on field than you can maintain . Your field should max out at 2 " Koa ' ki Meiru ' s " requiring maintenance with multiple " Cores " in play as well as an alternative cost ready in hand . With this in mind it would be wise to play multiple cards of the same Type , making your field easier to maintain . However , with the release of Xyz Monster s , you can simply overlay any " Koa ' ki Meiru " Monsters that you may not have a maintenance for . Beatdown uses a different lineup , using a minimum of control but only the best in the form of " Koa ' ki Meiru Rooklord " and " Koa ' ki Meiru Drago " . The main attackers are " Koa ' ki Meiru Bergzak " , " Koa ' ki Meiru Powerhand " and " Koa ' ki Meiru Rooklord " . With the addition of " Koa ' ki Meiru Urnight " from " Absolute Powerforce " , you gain a swarm / toolbox element . " Koa ' ki Meiru Ghoulungulate " is nice protection but your tribute fodder is best used on " Rooklord " . Spell / Trap protection is a better option . Weaknesses . Because " Iron Core of Koa ' ki Meiru " may often be in the Graveyard it is vulnerable to cards that can banish it 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 a card or discard a card from your hand at the End Phase , leaving your 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 ) . A good way to avoid problems with this is to keep a duplicate of the specific monsters in your hand - usually , " Koa ' ki Meiru " Monsters require you to reveal a monster of the same type so you can reveal a duplicate or another " Koa ' ki Meiru " of the same type . " Koa ' ki Meiru " monsters are very reliant on the hand and so cards like " Card Destruction " , " Mind Crush " , or " D . D . Designator " can completely disrupt the player ' s strategy and cards like " Trap Dustshoot " or even " Des Koala " can deal serious damage . 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 " . " Banish " Decks can banish " Iron Core of Koa ' ki Meiru " and so you have to rely on your revealing effect . To protect yourself from this , it is a good idea to have " Necrovalley " and a " Burial from a Different Dimension " in your Side Deck . " Hand Control " Decks present the biggest threat by being able to specifically remove assets essential to the Deck . Playing Tips . This Deck revolves around " Anti - Meta " . Obviously , the most important card in the Deck is " Iron Core of Koa ' ki Meiru " , so having three in your Deck is a must . Most of the monsters are used against Effect Monsters , mostly DARK and LIGHT monsters , since they are the commonly used Decks ( " Infernities " , " Lightsworns " , " Blackwings " etc . ) . Most Koa ' ki Meiru Decks should focus on the negation effects of " Koa ' ki Meiru Wall " , " Koa ' ki Meiru Sandman " , and " Koa ' ki Meiru Guardian " and the card advantage and swarming effects of " Koa ' ki Meiru Crusader " and " Koa ' ki Meiru Urnight " using the other " Koa ' ki Meiru " Monsters according to the Deck ' s main strategy . In addition , " Koa ' ki Meiru Ice " and " Koa ' ki Meiru Tornado " are wonderful in punishing your opponent ' s powerful Special Summoned Monsters . " Koa ' ki Meirus " can also work well with support for Equip Spell Card s . Using cards like " Hidden Armory " , " Iron Core Armor " can be recycled just as much as the " Iron Core " itself . " Core Blaster " is also extremely powerful , and even a single copy could destroy decks that focus heavily on LIGHT and DARK monsters . " Koa ' ki Meiru Bergzak " works very well with any ATK - boosting effect , and " Iron Blacksmith Kotetsu " fits on the deck since it ' s a Beast - Warrior . " Trade - In " can work well if you are using " Beast King Barbaros " or " Grandsoil the Elemental Lord " to reveal for " Koa ' ki Meiru Urnight " and " Koa ' ki Meiru Crusader " . Other Level 8 monsters to work with " Trade - In " are " Koa ' ki Meiru Valafar " and " Koa ' ki Meiru Maximus " . It would be wise to include cards that return monsters and other cards to your or your opponent ' s hand . For example , " Compulsory Evacuation Device " or " Penguin Soldier " can both remove threats from the field or keep a " Koa ' ki Meiru " alive for a turn or even using it for the maintenance . Usual " Anti - Meta " tricks like " Grave of the Super Ancient Organism " or " Royal Oppression " work fairly well , since " Koa ' ki Meirus " can maintain a solid game even without Special Summoning . Although most " Koa ' ki Meiru " monsters have difficulty staying on the field , a few of them work incredibly well together , sharing types or common reveals that help ensure their survival on the field . However , because most are level 4 , they can be used for an Xyz Summon before they are destroyed during the End Phase . Finally , a few cards have the heavy cost of discarding a Spell Card from your hand ( like " Summoner Monk " , " Cursed Seal of the Forbidden Spell " and " Chiron the Mage " ) , but " Koa ' ki Meiru " Decks can recycle the " Iron Core of Koa ' ki Meiru " as long as they want to , making these much more consistent than any other Deck . Recommended Cards . " See also : Rock Stun . "