Karumonix, the Rat King is a Legendary Creature from the Phyrexia All Will Be One set for Magic the Gathering. This is perhaps the best Rat creature ever printed thus far for EDH, especially for decks built around the Poison Counter mechanic. Let’s take a look at how powerful this Rat could be in the format, thanks to the debut of the Toxic mechanic in this return to Phyrexia.

The Rat King is a 3/3 body that with a mana value of three, costing one generic and two Black mana to cast. Not only does he have Toxic 1 himself, but other Rats you control also now have Toxic 1 when he is in play. Plus, when Karumonix enters the Battlefield, you dig five cards deep into your library, reveal any number of Rat cards among them, put them into your hand, then put the other cards at the bottom of your library in a random order.

So, what is Toxic? It’s basically Infect taken to a new level. While Toxic doesn’t deal damage to creatures in the form of -1/-1 counters like Infect, when a creature with Toxic deals combat damage to a player, it deals not only its regular damage, but adds a poison counter to that player, too. Just as it always has been, once a player accumulates 10 poison counters, that player loses the game.

How good is the Toxic ability compared to Infect?

While Toxic is certainly a powered-down version of Infect, because Rats can swarm so efficiently, it doesn’t take much to see Toxic Rats as a legitimate win condition. I am happy that you can’t simply use pump spells. However, fellow Legendary Rat Ashcoat of the Shadow Swarm could come out of the woodwork to boost this deck further in EDH; thankfully, Ashcoat isn’t Modern or Pioneer legal. 

In any case, you will need several separate attacks from Toxic creatures to take out a player, even with creatures with Toxic 2 or more, so it’s at least balanced. Also, the Toxic ability is seen throughout the entire All Will Be One set, on many Phyrexian and Mite creatures. In any case, Toxic will make Rats a competitive creature tribe more competitive in both the short and long term.  It will be interesting to see the interplay between Mites and the three Phyrexian Rats in the upcoming Standard.

Overall, Toxic is a bit more balanced than Infect because each creature will only deliver one poison counter. With Infect, you could use power-pumping spells to one-shot a player. With Toxic, this is not nearly as simple of a proposition. That said, the Toxic ability and the Rat King still can finish players off with one fell swoop with enough setup.

Are There Good Rat Creatures in Phyrexia: All Will Be One?

So, how much support does the Rat King get in the same set? Besides Karumonix, there are only two other Rats in the entire All Will Be One set. However, they are both decent creatures. One is the common Blightbelly Rat, a two-mana Phyrexian Rat that has a 2/2 body with Toxic 1. When it dies, you get to Proliferate, meaning you get to choose any number of permanents with counters on them and put another one of those counters on it. This has perfect synergy with Poison counters, so this would be a perfect inclusion as a full playlet (four copies) in a deck with Karumonix and an auto-include in any Karumonix Rat Tribal deck in Commander.

The second Rat is the uncommon three-mana Chittering Skitterling, a 1/4 Phyrexian Rat with a Corrupted ability. These Corrupted abilities are only active once an opponent has three or more poison counters. This ability allows you to sacrifice a creature or artifact to draw a card, as many times as you would like, on any player’s turn. Since you’re going to be dealing with Poison counters in any deck which runs Karumonix, the Rat King, this seems like a solid enough inclusion, at least with one or two copies. It’s also an auto include in any Karumonix Rat Tribal deck in EDH.

I would’ve liked to see a couple more Rats in the set to support the Rat King, but these inclusions are decent enough to see play. The free sacrifice outlet to draw cards, even with the Corrupted restriction, is a heck of a card to have at uncommon! Having played with cards with Toxic during Phyrexia All Will Be draft and sealed play, I found that three poison counters isn’t at all hard to get on an opponent rather quickly.

How Good is Karumonix the Rat King in EDH?

In EDH, Rats already have a few pretty good choices for their Commander. But, as good as the next newest Rat Tribal commander in Ashcoat of the Shadow Swarm can be, none of the existing options measure up to the game-ending potential that is offered by Karumonix. The beauty of this Rat King is that all he has to do is be in play. He doesn’t even have to enter play until you already have enough Rats to poison everyone else out of the game. 

That said, Ashcoat is going to be crucial to the Karumonix game-plan, as when he swings, the Warlock powers up your attacking Rats to an absurd degree. Plus, his ability to mill four cards and return two Rats back into play is going to also be extremely helpful.

Marrow-Gnawer is clearly still the best non-Karumonix Legendary Creature, as we’ve already talked about in the Modern version of Rat Tribal. Ink-Eyes, Servant of Oni, Patron of the Nezumi, and Nashi, Moon Scion’s Sage should all feature in a Karumonix EDH deck in a supporting role, as well.

While Greasefang, Okiba Boss decks are better equipped for swarming Vehicles, there exist Rat Colony builds of the deck. These builds are more than likely to acquire a copy of Karumonix, the Rat King for an alternative win condition.

Almost upon spoiling, there was already the shell of a Karumonix, the Rat King EDH deck, with Sheoldred, the Apocalypse listed as the Commander posted on MTG Goldfish. It was centered around Relentless Rats. Since then, Karumonix led EDH decks have split into four distinct categories. Rat Tribal is the #1 choice, with Rat Colony being a close second. There are also Relentless Rats builds, but Infect/Toxic builds are a distant fourth. 

Of course, like every Tribal deck in EDH, these decks will evolve as we get more support for the Rat tribe in future releases. For example, Wilds of Eldraine introduced five more Rat creatures into the game. One of them is a Legendary Creature, Lord Skitter, Sewer King, who helps make more Rats while also exiling cards out of an opponent’s graveyard. He’s a great compliment to any Rat deck, but especially Karumonix.

How Good are Rats as a Tribal Modern Deck?

Karumonix, the Rat King appears to be the missing piece that Rat Tribal needed to be a serious threat in Modern. When he was first spoiled, I was excited to see what Standard brews would emerge. So, with how much scarier Rats have become as a Tribe in EDH, I felt that this Legendary Creature could even be at the core of a Rat deck in Standard, Pioneer, or even Modern.

This isn’t just wishful thinking for a relatively underpowered and under-supported tribe. Rats have long been a niche, but fun Tribal deck in the Modern Constructed format. This is partly due to the high power level of Pack Rat, which can continue to copy themselves at the cost of three mana and the discarding of a card. Other Rats stack hand-control effects. Burglar Rat forces an opponent to discard a card. Chittering Rat forces an opponent to put a card from their hand back on top of their deck. 

There’s also Nezumi Shortfang, who can tap and for two mana force an opponent to discard a card. Shortfang is particularly fun once your opponent has no cards left in hand, transforming into Stabwhisker the Odious. While it doesn’t happen often, when it does, it has a similar effect to the classic card known as The Rack. Like that artifact, each turn your opponent has fewer than three cards in hand, they take damage. 

The Rat tribal deck also has Piper of the Swarm, which gives all Rats menace. This means it takes two or more creatures just to block one Rat, plus a couple of other good abilities. There’s also the Legendary Marrow-Gnawer who gives Rats fear, meaning they can only be blocked by Black or artifact creatures. But, its tap ability is really why you play this, allowing you to sacrifice a single Rat to put X 1/1 Rat creature tokens into play, where X is the number of Rats you control.

The deck is then rounded out by many copies of Rat Colony, of which you can play any number in a deck. This is typically around the thirteen copy mark. For each other Rat you control, Rat Colony gains one power. 

For non-creatures, the deck typically only plays Aether Vial, in order to be able to cheat out cheap rats every single turn. The rest of the deck is the mana base, four of them being Swarmyard which can tap to regenerate a target Rat, and four more being Mutavault, which can animate themselves and also become Rats. 

How Good is Karumonix the Rat King in a Modern Deck?

There’s plenty of room for Karumonix to enter the fray here. You could drop the Chittering Rats package entirely in order to keep the mana curve the same. Of course, Phyrexia All Will Be One will give us other options to replace copies of Nezumi Shortfang or even Rat Colony to shore up the overall power level of the deck. 

But, Karumonix works very well alongside Marrow-Gnawer’s ability to produce a ton of Rats in a hurry at instant speed. It doesn’t take very many Rats to deal ten poison damage, especially if your Burglar Rats and whatever other hand-control Rats which remain are slowing your opponent down to a crawl.

It’s also possible that Karumonix and other Rats from Phyrexia All Will Be One and Wilds of Eldraine might make this Rat Tribal deck actually competitive. That means you’ll see more typically hand removal such as Thoughtseize or Inquisition of Kozilek instead of Burglar Rat, Nezumi Shortfang, or Chittering Rats entirely. This allows the deck to focus entirely on Pack Rat, Rat Colony, and Piper of the Swarm building the Rat army. You may even see some removal included for a more balanced, competitive feeling deck. 

Sadly, as of October 2023, no competitive deck lists have emerged with Karumonix, the Rat King in Modern, Standard, or Pioneer. On the other hand, previously mentioned Lord Skitter has made its way into Standard, thanks to its cheap Token production. So, it’s only a matter of time that someone puts together a successful Rat Tribal deck.

On that note, Saffron Olive did build a fascinating Rats deck in Modern around Aether Vial, Karumonix, and Pack Rat, plus a couple other Rats from Wilds of Eldraine. Sadly, it didn’t fare well against the Up the Beanstalk decks at the time, but it did go undefeated against Rakdos Scam (Grief/Fury/et al). But now, with that stupid enchantment banned in Modern, along with Fury, it may be worth taking another shot with this Rat strategy. Seth had some neat ideas that deserve further exploration. 

What do you think of Karumonix, the Rat King? I feel that he is a very underrated Commander, although he definitely has his fans. The return to Eldraine has brought several more key pieces to the Rat Tribal family, each which deserves further treatment. It’s only a matter of time before the Rats infest a competitive format. 

~ Amelia <3

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