The Koa'ki Meiru have always wielded some amazing combos, but they've been plagued by inconsistences galore. Koa'ki Meiru Urnight's a Beast-Warrior Level 4 monster that can Special Summon whatever you want from the deck for freeā€¦ as long as you have Iron Core of Koa'ki Meiru. The Iron Core's essentially wasted space in your hand: you can't activate it, and it doesn't do anything by itself. On top of that, all of the Koa'ki Meiru monsters self-destruct if you don't hold up their maintenance costs, usually by revealing a monster of the matching type: in Koa'ki Meiru Urnight's case that means having another Beast-Warrior in your hand, or discarding an Iron Core.

It's a balancing act, to say the least.

Luckily, Primal Origin gave Koa'ki Meiru players a card from the heavens: Diamond Core of Koa'ki Meiru. Jason already wrote an entire article on why Diamond Core's so great, but I'll give you a brief rundown. First and foremost, Diamond Core can search out any Koa'ki Meiru card, straight from your deck. That's awesome because in the past, one of the biggest issues with Koa'ki Meirus was that you had to max out on copies of the ever-unsearchable Iron Core. Additionally though, Diamond Core gives you easier access to your other Koa'ki Meiru monsters when you already have Iron Core, preventing awkward pass-and-go turns from happening.

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Beyond that, Diamond Core has a second effect where you can protect Koa'ki Meirus from being destroyed. It's useful for a couple of reasons. Naturally it'll protect you from the likes of Torrential Tribute, Mirror Force, Bottomless Trap Hole, and so on, but it'll also help you deal with those dreaded maintenance costs. Even better, Diamond Core gives the middle finger to the increasingly popular Fire and Ice Hand. Neither of them can Special Summon the other if they fail to destroy a card, so making your Koa'ki Meirus immune to Fire Hand cuts them off. Most decks can't get around the Hands without making awkward Xyz Summons, so this added, free bonus is totally awesome.

Setting the Groundwork
There are definitely a bunch of different ways to go about building a Koa'ki Meiru deck, and right now there isn't a general consensus on what version's the best. Rather than go over every single build that isn't today's, I figured it'd just be better to take you through the process that led to this build. Of course, there's lots of testing thrown in here and I didn't just pull this build out of nowhere, but going step by step through the deck should be beneficial.

Starting out with the Koa'ki Meiru cards that give the strategy its namesake, we want to accomplish a few things. There's a dangerous balancing act with Koa'ki Meirus, and as a result you're looking to maximize consistency and power without crowding too many awkward combinations into your starting hand. Koa'ki Meiru Urnight is your obvious combo-enabler, but it's important to pinpoint the best monsters to Summon with its effect. Our build will be using the following:

3 Koa'ki Meiru Urnight

3 Koa'ki Meiru Crusader

1 Koa'ki Meiru Ice

3 Diamond Core of Koa'ki Meiru

2 Iron Core of Koa'ki Meiru

Koa'ki Meiru Crusader is by and large the natural fit for Urnight. They're both Beast-Warriors, opening up a plethora of ways to search them out as well as one of the best themed Xyz Monsters out there: Brotherhood of the Fire Fist - Tiger King. Additionally, the single copy of Koa'ki Meiru Ice grants you easy spot removal as well as a way to make use of dead in-hand cards.

Lastly, I've gone back and forth with different numbers of Iron Cores, but two seems to be the right fit. After all, if you're restricted to constantly searching out Iron Core with Diamond Core as opposed to Urnight or Crusader you're really not getting the most out of Diamond Core.

3 Brotherhood of the Fire Fist - Bear

1 Brotherhood of the Fire Fist - Gorilla
1 Coach Soldier Wolfbark

3 Fire Formation - Tenki

1 Fire Formation - Tensu

Next up, a nine card Fire Fist engine is going to act as fuel for most of your plays. Bear gives you a steady stream of aggression, and opens up plays when you don't draw any Koa'ki Meirus. When you're forced to play cards like Iron Core - a totally useless card by itself - it's best to have stuff that offsets that blank slot by gaining you +1's. The last third of the monsters is going to be combo-enablers, and it's only a four card engine.

3 Tour Guide From the Underworld

1 Tour Bus From the Underworld

This is actually the first deck I've used Tour Bus From the Underworld in, and that's because I try to stay away from Bus unless it's crucial to return stuff to my deck. With Koa'ki Meirus, Tour Bus can shuffle back Summons for Urnight as well as Fire Fist Bears, and that's awesome. Sure, you're going to draw it every once in a while, but Tour Bus is arguably better than Iron Core so it's not the worst draw in the world. But what's a Rank 3 engine doing in a Level 4 strategy?

Tour Guide's basically here for one reason: freaking M-X-Saber Invoker. This Rank 3 has had its ups and downs, but it's always been useful in Koa'ki Meiru because it brings out Koa'ki Meiru Urnight right from your deck. Consider the deck's most basic combo:

Starting hand: Tour Guide From the Underworld and Iron Core of Koa'ki Meiru

- Normal Summon Tour Guide, grab another Tour Guide, overlay for M-X-Saber Invoker

- Detach to Special Summon Koa'ki Meiru Urnight from your deck

- Reveal Iron Core in your hand to Special Summon Koa'ki Meiru Crusader from your deck

- Overlay Urnight and Crusader for Brotherhood of the Fire Fist - Tiger King

- Set Fire Formation - Tenki from your deck with Tiger King's effect, and activate it to search out whatever your heart desires

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In layman's terms, you turned your two cards into four cards, the last of which could potentially gain you even more +1's. What you grab with Tenki really depends on the situation. For example, the easiest route is simply adding the second Urnight to your hand, threatening one or two more Rank 4's your next turn (depending on whether Invoker survives of not).

Alternatively, Fire Fist Bear's always an option, capable of dismantling whatever your opponent throws at you. With Diamond Core in the mix, adding a second Crusader to your hand isn't even that bad a decision either. Crusader can run over an opposing monster, which in turn adds your Diamond Core back to your hand, which in turn searches your deck for another monster.

Realistically, though, this deck won't function on just one or two combos alone. We're going to be fleshing out the rest of the build with strong spells and traps, fined tuned to a post-Primal Origin metagame. Let's take a look:
DECKID=100286Besides being, you know, Beast-Warriors, the Fire Fists and Koa'ki Meiru share another trait in common: they both find big benefits in winning battles. Brotherhood of the Fire Fist - Bear, Brotherhood of the Fire Fist - Gorilla, and Koa'ki Meiru Crusader all make instant +2's whenever they win a fight (that's one plus for the monster they destroyed, and one for the card they add or set with their effect). Having so many monsters like that in one deck, it only makes sense to run three Forbidden Lance. Because they're Beast-Warriors, though, I've added two copies of Horn of the Phantom Beast as well. Any of the three monsters I just mentioned create devastating +3's when equipped with Horn, and the majority of your opponent's won't see it coming.

Also, a quick note: Brotherhood of the Fire Fist - Tiger King backed by one Fire Formation (like the one it sets when you Summon it) along with Horn will allow you to trade off with Leo, Keeper of the Sacred Tree.

What's Missing
It's only fair that I address what isn't in the deck after I spent so much time building up what is. For starters, you won't find any Mystical Space Typhoons in my list. Why? For two reasons. First of all, you really don't care about normal backrows in Game 1 because Diamond Core and Forbidden Lance prevent any attempted shenanigans barring Solemn Warning. The second reason is that Artifact Sanctum and Artifact Moralltach are running around everywhere and in everything. You simply cannot afford to blind Space anymore, and as a result it's better to leave Mystical Space Typhoon in the Side Deck until you figure out if your opponent's playing Artifacts or not.

Pot of Duality's also not included, but that's definitely up for debate. On one hand Duality ups the overall consistency of your strategy, digging deeper into your deck to get to those combo pieces. On the other hand, Duality's completely dead if you already have your combos ready to go, or you're in the mid to late game when you really need to Special Summon. At the end of the day I felt the deck was consistent enough and didn't need Duality, but if you really want to play it then feel free to.

The last big thing that's been excluded from this build are any defensive Rank 3's. M-X-Saber Invoker's only good if you have a follow-up play or an Iron Core in hand. Alucard's really good, but not when you're going first. Sometimes you'll open up with Tour Guide and no other monsters, and it'd be nice to have a Wind-Up Zenmaines, Mechquipped Angineer, or something similar. Alas, the Extra Deck is extremely tight, and I just couldn't justify dropping anything. If you feel like exploring your choices I'd suggest cutting the Brotherhood of the Fire Fist - Cardinal or Photon Papilloperative.

The Competitive Potential
I wanted to briefly touch on the Side Deck capabilities of Koa'ki Meirus before I wrap this up. Koa'ki Meiru Urnight can Special Summon any Koa'ki Meiru from your deck, and Koa'ki Meiru Drago's a prime target. This powerful Dragon acts as a one-sided auto-win against decks like Infernity, Artifacts, Choas variants, Lightsworn, and many others.

Drago wasn't plausible before Diamond Core because you have to reveal a Dragon from your hand to keep it alive, but now you can just banish Diamond Core to make sure Drago sticks around. Taking into account that all your Koa'ki Meirus have at least 1900 ATK points I'd have to bet that Drago locking your opponent out of the game for one or two turns will often win you the duel.

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As for other Side Deck cards to look into, Fire Hand and Ice Hand are always welcome. They're really stellar at burning through your opponent's resources at an extremely fast rate, and following them up with huge combos is too good to pass up. Rivalry of Warlords is also a great card available to you, completely shutting down strategies hinging on different monster types like Madolches, Atlantean Mermails, and Spirits.

I love Koa'ki Meiru, and I was super excited when Diamond Core was revealed to us a few months back. It's such a cool card, and it really solves almost every single one of Koa'ki Meiru's problems. The only better support they could get would be an Iron Core that actually did something useful, but I doubt that'll ever happen. Regardless, this deck's surprisingly competitive and I'd strongly suggest giving it a go if you have some free time.

-Doug Zeeff