Legacy: Cosmogoyf Memnite Combo - Deck Tech and Sideboard Guide

Greetings, Legacy community! This week was full of surprises for Legacy, considering Undercity Informer was banned, and it is still too early to tell what the format will look like from now on. So, while we're waiting for the dust to settle, let's take a look at a very exotic build.

Here at Cards Realm, we cover all types of decks. Decks from the top tiers, innovative decks with new cards, decks that can still grow in the meta, and, every once in a while, unusual lists that want to win in unconventional ways. These decks often show how Legacy's huge card pool allows for insane ideas. So, today, let's go over one of these uncommon strategies!

The first time I played against this combo, a few years ago, I didn't understand anything that was happening. Leyline of Transformation early? Naming Sliver? And, on turn 1, my opponent played a land, Elvish Spirit Guide, and Hatchery Sliver, and replicated so many Memnites I couldn't keep track of them all! This deck was clearly a meme then, as it relied on getting the perfect hand early on, but seeing it in action was pretty fun.

If it's still not clear, this is how the combo works: you open with Leyline of Transformation in play and name Sliver as your creature type. Like so, all your creatures will be Slivers. If you have a Hatchery Sliver in play, your Memnites, which are now Slivers, have Replicate 0. Profit!

A while after this experience, I was looking for something to talk about when I stumbled upon this marvelous work. It actually won a League trophy in the hands of a player called weekends:

The infinite Memnite combo is there, but there was something else as well. Considering this deck centers around a combo that plays Leylines, it makes sense to play Serum Powder as well. After all, this way you'll find your key card more often. And you'll also be able to exile a bunch of cards at once. So, why not take advantage of that to win the game through an alternative win condition?

Enters Cosmogoyf. If you use Powder even once, Goyf is already a 7/8 monster for 2 mana, and it gets +7/+7 for each time you use Powder after that. It can even be lethal (albeit a bit risky) straight away because of Spoils of the Vault. Usually, you'll play this card to find your main combo pieces, but it can also exile many cards at once.

So, here it is: the main combo, Serum Powder, and Spoils of the Vault (to make this strategy more consistent), as well as Cosmogoyf as an alternative win condition.

There's still space for other tools, though. Thrumming Hivepool allows you to kill the opponent in the same turn you create all your Memnites, as they'll have Haste. Once Upon a Time and Brainstorm will help you find your key cards, while Worldly Tutor will just get them for you! Thoughtseize and Disruptor Flute offer protection/disruption, and Elvish Spirit Guide completes this whole mess by adding acceleration.

Back when MTG was still being developed, WotC's R&D team came up with three player profiles: Timmy, who likes playing big creatures and high-impact spells, Spike, who is naturally competitive and always wants to play the best deck, and Johnny, who likes complex interactions and complex decks, often the most intricate combos possible.

This deck is a gift to all Johnnies in the world: if you like decks that aren't necessarily the most competitive but are incredible when all pieces fit, this infinite Memnite machine is perfect for you!

There's a thing we say whenever we have to discuss how to mulligan with combo decks: "This is a combo deck, mulligan after your combo."

This is particularly true in this case because, besides your standard mulligan, you'll also have Serum Powder.

This deck needs Leyline of Transformation, so you can "Serum Powder" or mulligan until you have 4 or 5 cards to make sure you have it. In certain cases, you can consider keeping hands that don't have this Leyline to try to play it for its full cost later on, but this is far from ideal.

Let's see a few examples.

You can't ask for more than this (maybe just one extra mana). This hand is 1 land away from putting the combo in play on turn 2. In particular, if you draw Cavern of Souls, you can simply ignore counterspells: Hatchery Sliver can't be countered, and, because of the way Replicate works, countering the original Memnite doesn't interfere with the Replicated copies. Verdict: You should keep it.

This hand already has the Leyline, though it doesn't have the rest of the combo. In any case, it can dig through the deck after the missing pieces. You'll play Misty Rainforest into a Surveil land and Once Upon a Time. Verdict: You should keep it.

This hand doesn't have the Leyline, though it has the rest of the combo. We just can't keep it. Verdict: You should mulligan it.

This hand also doesn't have the Leyline, but it has Serum Powder. Verdict: Serum Powder. Let's see what would come afterward:

Ok, no deal. Verdict: You should mulligan it.

As this deck is pretty peculiar and not mainstream at all, the sideboard we'll show you is pretty unconventional, and some of it was quite intriguing. Let's take a look at the most obvious picks first.

Surgical Extraction is the basic answer against graveyards. Massacre is an answer to the increasingly threatening Energy decks that have been conquering space in Legacy and can put a lot of pressure on you. Cabal Therapy, Boseiju, Who Endures, and Chalice of the Void are more disruption and answers to other combos. Please note that a Chalice for 0 counters the original Memnite, but it doesn't affect the Replicated copies.

Ok, now let's move on to some unusual picks: Artificial Evolution is an alternative way to put the combo in play. You'll change Hatchery Sliver's text from Sliver to Construct and can still Replicate your Memnites. This will work when you expect the opponent to play enchantment removals to deal with your Leylines.

Green Sun's Zenith works as extra copies of Hatchery Sliver when you need to be more consistent, but it can get you Cosmogoyf as well. Finally, Screeching Sliver is an alternative way to win if you're facing an unusual issue: if you can't go over Tamiyo, Seasoned Scholar's first ability!

Dimir Tempo

Game 1 could bring you an unusual problem, as we mentioned above: Tamiyo, Seasoned Scholar. Her +2 ability prevents your infinite Memnites from attacking. If that happens, you might have to move on to plan B: Cosmogoyf. Please note you can Replicate a Goyf that is also a Sliver and give it haste and double strike with Thrumming Hivepool.

This is a problem you'll try to deal with post-side with Screeching Sliver.

In:

Out:

Show and Tell

Your key card in this matchup is Cavern of Souls because if Hatchery Sliver comes into play uncounterable, they won't be able to stop your Memnites. You can even use them to absorb an Emrakul, the Aeons Torn's Annihilator! Disruptor Flute will both delay Show and Tell and stop Sneak Attack for good.

In:

Out:

Boros Aggro

If you have the right cards, they won't have many ways to stop your infinite 1/1s. On the other side, they won't give you a lot of time to dig through your deck after your pieces. Your Spoils of the Vault is even riskier considering you won't have many life points to work with in this matchup. Post-side, they'll have a few answers to your combo, including Pyroblast for your Leyline, but you can ignore Deafening Silence. As your Leylines will be at risk, you must get some alternatives for the combo, particularly Artificial Evolution.

In:

Out:

Doomsday

If they resolve their key card, your only options are putting the combo in play with Thrumming Hivepool as soon as you can or breaking them with Boseiju, Who Endures or Disruptor Flute. Chalice of the Void for 0 breaks some of their combo lines. As they play discards, Zenith could help you find your Slivers.

In:

Out:

Trini Tron

The biggest issue in this matchup is that you can't put the combo in play when The One Ring is active, and, if they get enough mana, Ugin, Eye of the Storms can exile the Leyline. If you can play some Serum Powders, a turn-1 Cosmogoyf can be lethal! Boseiju, Who Endures is basically a 2-mana Vindicate against this opponent.

In:

Out:

This is not the best deck in the world, and you shouldn't get it if that's what you want. But it can win games in Leagues and is a lot of fun when it works. Sometimes, you don't want the most competitive list. You just want to set up some dominoes and watch them fall.

What do you think? Tell us your thoughts in our comment section below.

Thank you for reading, and see you next time!