Brewing Satoru, the Infiltrator in cEDH
Satoru, the Infiltrator by Heonhwa Choe
Satoru, the Infiltrator is an interesting card: it's a cheap commander, which I love, and it offers a unique card drawing angle, which is what makes it a consideration as a commander for cEDH.
Free Creatures With Satoru
The first thing Satoru does is make any creature that naturally costs no mana, such as Ornithopter, draw a card when it enters the battlefield. This allows you to include a lot of cards that basically have the cycling cost of "control your commander", though, awkwardly, you have to control Satoru when the spell resolves to actually draw the card. You can thereby run a "smaller deck" by playing every free creature you can find. Doing so isn't free: you get a lot less information about what your hand will ultimately look like when you're deciding which hands to keep, and you need hands that have two lands so that you can cast your commander, but then you might draw too many lands when you cash in your free cards.
I often wish I could play more cards rather than fewer cards in my Commander decks because I have access to some many tutors that my deck might actually be better if I could include more specific tools to find, so the "smaller deck" angle isn't a big draw for me. Where I get more interested is when we can abuse these cards.
There are a total of 13 creatures that you can naturally cast for free in a Dimir Commander deck: four that cost zero, and nine that cost X. The four that cost 0 are much better because they stay on the battlefield when we cast them for 0, unlike any of the creatures that cost X, which each enter with X +1/+1 counters. It's generally better to have a creature on the battlefield rather than in your graveyard, especially because cards like Retract and Paradoxical Outcome can return all of your free creatures to your hand so that you can use them to draw more cards with Satoru.
You can lean into this plan by playing Retract, Hurkyl's Recall, and Paradoxical Outcome, and then you can get a lot more value out of those cards by playing stuff like Chief Engineer or Etherium Sculptor that allow you to turn the creatures that cost X into creatures you can cast for no mana that stay on the battlefield rather than dying immediately. Alternatively, you can just let them go to the graveyard and use them to supercharge Yawgmoth's Will.
It's very likely that Satoru decks want to play all 13 free creatures, but I could imagine building the deck in a way that doesn't use all of the ones that cost X.
Another card I really like for taking advantage of this shell is a card I've never seen played in another cEDH deck: Ugin's Mastery.
With Ugin's Mastery in play, all of your free creatures will also cause you to manifest, and because the manifest isn't a token, it will trigger Satoru as well, so you'll draw two cards for each of your free creatures.
Satoru's Ninja Synergy
Another class of card that plays very well with Satoru is Ninjas. Whenever you use a ninjutsu ability, a creature will enter without having been cast, so it will trigger Satoru even though mana was spent. If you pick up another creature that was cast for free, you'll be able to draw again when you cast it.
If you have two creatures with ninjutsu in your hand and an unblocked creature, you can return that creature to play, use a ninjutsu ability, draw a card, then return that Ninja to activate the ability of the other one and draw another card, and keep alternating between the Ninjas for as much mana as you have. For this reason, Ninjas that only cost one mana to activate their ninjutsu ability are nice.
Sakashima's Student can win the game by looping with another Ninja if there's a Dockside Extortionist around for it to copy. One unusual Ninja that's a particularly good fit for this deck is Orochi Soul-Reaver. This will make each creature that damages a unique opponent make a Treasure and manifest a card, and manifesting will draw another card, so this can draw as many as five cards (one for itself, three for the manifest triggers, and one for recasting the creature you returned) the turn you play it under optimal conditions.
Because of the loops that are possible with multiple Ninjas and the scaling payoffs of cards like Yuriko, the Tiger's Shadow, there's incentive to go further into Ninjas if you're going to play some of them, but you can also stick to only playing the most efficient ones.
Satoru Graveyard Shenanigans
Another good way to trigger Satoru is with creatures that enter the battlefield from the graveyard. If you want to take advantage of these cards, you'll probably want ways to get them into your graveyard without casting them from your hand, such as looting effects, and you'll also probably want ways to sacrifice them so that you can trigger them again without waiting for them to die.
This means taking advantage of these cards can take up a lot of space in your deck, but they can also draw a lot of cards. Some good options include Forsaken Miner, Bloodsoaked Champion, Cult Conscript, Bloodghast, Nether Traitor, and Prized Amalgam. The best ways to sacrifice these would probably be Phyrexian Altar and Altar of Dementia, but you could also consider something like Braids, Arisen Nightmare if you're looking to be a little less explosive.
Reanimation spells and other cards that manifest or cheat cards onto the battlefield will also trigger Satoru, which means a card like Reanimate will be serviceable even if you're only returning a mediocre creature, because you'll also draw a card.
Satoru with Flicker Effects
Another angle that I'm a little less optimistic about is blinking: if you have a card like Thassa, Deep-Dwelling, you'll draw a card each end step when you exile and then return a creature. Without white, I don't think there are enough good cards in this space, and most of the things you can do here seem a little slow to me for cEDH, but it's something to keep in mind. Without going that deep, this makes Displacer Kitten a very strong card for the deck, as you'll draw a card whenever you target a creature with Displacer Kitten. This makes cards like Spellseeker and Trinket Mage, which are strong cards for the deck anyway and can also easily retrigger Displacer Kitten when targeted, very appealing.
Trinket Mage + Displacer Kitten in particular will not only let you play all of your free noncreature artifacts, but also draw a card for each of them, and then you'll be able to use that mana to play all of your one-mana artifacts. If you need to go further, you can sink some of that mana into Sensei's Divining Top and fetch it with Trinket Mage, which creates a reasonable likelihood that these two cards will probably win the game.
Building with Satoru
All this is to say that there are several reasonable approaches to drawing cards with Satoru, and each kind of asks you to build around it in a way that wants some commitment with dedicated support cards, so while you could include a few of the best of each direction, you'll generally want to pick one or two to focus on.
Because Satoru wants to play 13 creatures that cost 0 that most decks don't want to play, it's naturally a particularly good Ad Nauseam and/or Bolas's Citadel deck, and of course, because it's a Dimir deck, it will want to include Thassa's Oracle, Demonic Consultation, and Tainted Pact, and it will usually look to end the game with those.
When it comes to building the deck, there's a lot I'm not sure about: I'm not sure which Satoru engines are worth leaning further into, and I'm not sure how many different ways you want to have to win the game, so I have a build that I'll go over, but I don't want the precise list I have to overshadow the points above about considerations for the deck, which is why I started there. As for where I'd start with this, my list, broken down as usual by what the cards do:
All The Free Creatures
These are basically a given, or at least a "play until proven otherwise."
I think a small Displacer Kitten package is pretty exciting here:
Another package that I think plays well with that, but also stands on its own, is the Bolas's Citadel/Aetherflux Reservoir package.
This package is nice because the 0s play independently well with each of The Reality Chip, Aetherflux Reservoir, and Bolas's Citadel, and Bolas's Citadel is generally kinda cute with Satoru, since Satoru will trigger on any creature you play from Bolas's Citadel. This package is another reason to consider Etherium Sculptor, which I don't currently have in my list, but would both make the X creatures better and create an infinite combo with Sensei's Divining Top and The Reality Chip.
A core strength of this deck is how many cards it has that draw a lot of cards, especially when you factor in that you'll draw them more because of both having so many cards that just cycle and having a lot of tutors. These are the various card advantage engines outside of Satoru:
I'm a little skeptical of Retract without more support to keep the X creatures on the battlefield, but I want to try it out. The rest of these I think are pretty solid.
Drawing all these cards wouldn't do much for us without a way to convert them into interaction, so we need some premium counterspells. My current suite looks a little sparse, but it'll play like a deck with a few more since it's drawing so many cards. Still, I wouldn't be opposed to Dispel or Force of Negation finding their way into the deck:
Subtlety is nice because it draws a card when evoked if you control Satoru.
The other important piece to tie all this card advantage together is the ability to generate extra mana to use the cards:
Notably, this doesn't include any Signets or Talismans or anything because I'm looking to have two mana sources in my opening hand to get to cast Satoru, and those don't help with that, and if I include cards that don't help with that, I'm more likely to flood out after I cycle the free cards.
I'm not very confident in the Ninjas: with only a few of the 0-cost creatures staying on the battlefield, I think it might be hard to take advantage of them; still, I'd want to try a few:
A few more obvious cards, like the Thassa's Oracle combo pieces:
Tutors
And of course, the good black creatures:
It won't come up much, but if you play a creature with Dauthi Voidwalker, it will trigger Satoru.
To round the deck out, a bit of removal and some one-offs:
And of course, 25 lands, which can be found in the full decklist below.
View this decklist on ArchidektI think this deck has enough raw power and proven cards to win games despite a few experimental pieces, which may not speak highly of Satoru if the deck is capable of winning despite the cards that are included because of the commander, but it's less that I think they'll be bad and more that I have questions about them because they aren't proven the way that cards in most Dimir decks are.
I think there are some kinks to work out in terms of figuring out whether things like the KCI and Ninja packages are worthwhile and whether it's worth playing any of the graveyard stuff or leaning more into Etherium Sculptor type cards, but I think this is an interesting direction for Dimir.