I like both cards as I've used them both in The Scarab God and Nekusar, the Mindrazer. Having multiple Sidisi's in play is absolutely nuts but it's honestly just a matter of space for me. Finding cuts in the deck is just getting more and more difficult with each new set released.
Yeah, making cuts is definitely a challenge. Looking at your list, the only thing that jumps out is Gurmag Drowner, unless it's serving a purpose I don't know about, or has been performing particularly well for you.
Emry, Lurker of the Loch - Although the deck doesn't run too many artifacts, Emry can mill four of our cards at a cost between 1-3 mana. She can also tap in order for use to cast an artifact from our graveyard until end of turn. Since I've managed to continue reducing the number of noncreature cards in the deck, the amount of artifacts will definitely diminish. It's hard enough as it is looking for space in the deck to put in a card that will eventually be taken out. That being said, Emry is an amazing card - just not here.
Ayara, First of Locthwain - Definitely worth considering for the deck! Although her BBB is hard on a tricolored deck, her abilties more than make up for it. With sufficient zombie tokens entering the battlefield, we can kill all opponents without needing to turn sideways.
Murderous Rider - Hero's Downfall on a creature is exactly the kind of thing this deck wants. As a bonus, it can be cast from its adventure for just 1BB as 2/3 zombie with deathtouch that goes back to the bottom of the library when it dies. 100% going in this deck.
Syr Konrad, the Grim - Another amazing card for the deck. Everytime we mill ourselves or one of our creatures die, we get to deal 1 damage to each opponent. This is something that happens quite often in the deck and that damage definitely adds up. He's a bit costly at 5 mana but he's a 5/4 so he more than makes up for it. On top of that, he can mill everyone for 1 for just 1B.
The Cauldron of Eternity - Although I'm trying to reduce the amount of noncreature spells in the deck, this artifact is very good here. Considering the deck is a self-mill deck, more than likely it'll cost just BB. When our creatures die, they go to the bottom of the library. The, for just 2B, T, and paying 2 life we get to reanimate any creature from our graveyard at sorcery speed. Definitely worth considering for the deck.
Steelbane Hydra - With all the mana the deck produces this can definitely be cast with a healthy value of X. It can then be used as removal for any unwanted artifacts or enchantments on the battlefield. And, if it runs out, it can just be recast from the graveyard later one.
Calculating Lich - Calculating, indeed! This definitely fits in both the Main Build and the Zombie Build but it'll more than likely go in the Zombie Build. Not only does this hurt opponents when they attack each other, but when we attack with a horde of zombies, opponents will lose life regardless if they block or not. So they'll lose life and then they'll have to deal with the horde. I can even look past the high mana cost since these decks generate so much mana.
Acolyte of Affliction - It only self-mills 2 but it can return any permanent to our hand which is incredibly versatile in the deck since it can recover an artifact, enchantment, land, or planeswalker. It has an okay body at 2/3 for its ability and casting cost. It's not a definite include, but is worth testing.
Atris, Oracle of Half-Truths - This creature is win/win in the deck. Getting cards in our graveyard isn't a problem. If a creature gets sent to the graveyard, Sidisi creates a zombie. This deck doesn't blink but it does sacrifice creatures and reanimates them so we can definitely use his ability a couple of times even though it's an enter-the-battlefield one.
Dryad of the Ilysian Grove - The deck doesn't really suffer in terms of getting color-screwed. But there are a couple of utility lands so being able to tap them for any colored mana can be useful. As a bonus we can play an additional land each turn. This allows us to drop a land from hand as well as play one from the graveyard with Muldrotha, the Gravetide.
Eat to Extinction - It's a bit overcosted at 4 mana but it exiles its target. It can also self-mill the top card of our library. So it does 2 things that are useful for the deck. It's also at instant speed, which is great.
Funeral Rites - Definitely worth considering for the Budget Build. You draw 2 cards and self-mill 2 cards for just 2B. You lose 2 life but that's negligible in commander.
Gravebreaker Lamia - Entomb on a creature is amazing even if the creature doesn't have flash. Additionally, lands we cast from the graveyard cost 1 less to cast so Muldortha and Havengul Lich love that. It's also a 4/4 with lifelink for 4B so it also has a great body for its cost, too.
Mindwrack Harpy - Great for the Budget Build, it self-mills us for 3 cards while also making all opponents mill 3 cards, which can be quite disruptive when left unanswered. It's also a 3/2 with flying for 3B which isn't bad, either.
Relentless Pursuit - Another good self-mill spell for the Budget Build since it self-mills 4 but you can save a land from those and put it into your hand.
Skola Grovedancer - Good to gain life, it's self-mill ability is a bit overcosted. I think it would've been fine at just 1G or even G. That being said, I think it could be good in the Budget Build as a way to gain life against more aggressive decks.
Thassa, Deep-Dwelling - A Conjurer's Closet on a body would be a great addition to the deck with all the creatures with enter-the-battlefield abilities. However, it'd need considerable testing just to make sure it pulls its weight and isn't just a pet card.
Tymaret Calls the Dead - It self-mills 3 cards at the end of our draw step for two draw steps. We probably won't be exiling any creature to create a generic zombie token. However, if we're able to keep a huge horde of zombies amassed, we can gain a huge chunk of life and scry deep into our deck by the time the 3rd lore comes into effect.
Underworld Sentinel - It's a roundabout way of reanimating creatures but at least any creature exiled under it won't be unrecoverable if our graveyard were exiled.
Also, I uploaded a video on my channel explaining the Main Build of my deck, for anyone interested in seeing a video instead of reading through the primer. The primer has way more information but the video is illustrative. You can find it here.
Fierce Guardianship - Having a free counterspell is no joke. Having Sidisi out is most of the gameplan getting a free Negate because of it is awesome.
Tidal Barracuda - It might help opponents outside of my turn but at least during my turn it's like Dosan the Falling Leaf. This helps me complete my game-ending combos without any kind of interaction from my opponents save from activated and triggered abilities. But for the most part, it's solid. It's also on a creature with a huge plus for this deck.
Sawtusk Demolisher - Is a Beast Within on a body if we mutate it. This deck has plenty of mutate targets on it. In fact, the best one is Sidisi herself. This helps me mutate Sidisi into a nonlegendary 6/6 with trample as a bonus. Meaning that I can clone Sidisi later on and not worry about the legend rule. It also makes it easier to attack with Sidisi to trigger her and not worry so much about her dying in combat.
Excavation Mole - It does self-mill 3 when it enters the battlefield but it's still a 3/3 with trample for 3 mana. I don't think it's that impactful in the deck given the rest of the cards in it and available for it that I'm already not running.
Gemrazer - A Naturalize on a body if we mutate it. There's plenty of mutate targets in the deck but Sidisi is definitely a great one for it. Mutating her with Gemrazer makes her a nonlegendary 4/4 with reach and trample, making it easier to send her to the red zone than as she currently is.
Titanoth Rex - Is a cheap way way to give a creature trample as well as drawing a card. However, if we reanimate it for free, it's an 11/11 with trample. That's definitely a threat in this format.
Gyruda, Doom of Depths - I probably won't use this as a companion even though you definitely could since Sidisi complies with its deck-building restrictions. However, you'd need to do some work changing a large part of the deck to accommodate it as the companion. That being said, it's great as 1/99 since it mills the entire table for 4 when it enters the battlefield and it can reanimate any creature milled this way if its casting cost is even.
Fiend Artisan - This can get huge in the deck. However, that's not necessarily why it's good for the deck. It's similar to Prime Speaker Vannifar, who's already in the deck. I can just sacrifice a zombie token, pay X and get any creature from my deck onto the battlefield. Definitely worth testing out to see if it's as powerful as Vannifar.
Skull Prophet - A 2-costed mana dork that can tap for either B or G but can also tap to self-mill for 2. For me, it's a bit slow for this deck. I'd rather have something like Bloom Tender for that mana cost since the deck already has multiple ways of self-milling that are much more efficient.
Parcelbeast - Has the potential of only costing GU via mutate. It's a good way to check the top of the deck for any lands. If we're manipulating the top of the deck then we might be able to get a land onto the battlefield each turn thanks to it and really accelerate our game (assuming we're also dropping our normal land per turn).
Brokkos, Apex of Forever - Is an amazing way to make Sidisi a 6/6 with trample since we can mutate Brokkos from the graveyard. If it gets self-milled, we can then mutate it onto Sidisi and make her even more dangerous. This is definitely something worth testing.
Emergent Ultimatum - Seems interesting. An opponent chooses 2/3 monocolored cards you look from your library. This can be used to find combo pieces but Urborg, Tomb of Yawgmoth is colorless so you can look for it. You'd have to look for Rune-Scarred Demon, Sidisi, Undead Vizier, and Razaketh, the Foulblooded since these are tutors on a body. Then, no matter what they choose, you can choose for any card you want. At first glance, BBGGGUU might seem costly to do so, but Rune-Scarred Demon alone costs 7 mana. Razaketh costs 8. And if used this way, this spell will net you 2 beaters, whichever of these 3 you get, as well as any card. It is a bit narrow, though, but it all depends on the combos of your own Sidisi build.
Titan's Nest - This card is able to give delve to all of our spells without an X in their casting cost. However, as I've mentioned multiple times, I don't like exiling cards with this deck because it plays with the library. That being said, lands not used that are in the graveyard can be used to reduce casting costs but I'd rather just generate the massive amount of mana the deck can already produce. The first ability of the enchantment is also too slow for the deck.
Zagoth Triome - With so many fetches in the deck, this can definitely be included even though it enters the battlefield tapped.
Archfiend's Vessel - In this deck it's going to a piece of cake to reanimate it, getting a 5/5 flyer for just B. However, in my deck at least, it's not impactful to try and find a slot for considering how hard it already is to make cuts in it. That being said, it might find a home in the Budget Build.
Carrion Grub - It'll be as powerful as the most powerful creature in our graveyard and it self-mills 4 when it enters the graveyard. Even then, it doesn't have any evasion of any kind and, just like with Archfiend's Vessel, I don't find it impactful enough to make a cut for it. That being said, it might find a home in the Budget Build.
Demonic Embrace - It's interesting in that it can be attached to Sidisi to give her a significant boost as well as making her harder to block. It can also be recast from the graveyard providing a discard outlet while doing so. This can get us a fatty in the yard to reanimate later. So it can be recast whether it was destroyed or self-milled.
Liliana's Devotee - As far as a zombie lord it's not bad and the triggered ability can get us yet another 2/2 zombie token for just 1B. I'd have to test and see if it's even worth a slot in the Zombie Build. It might go in the Budget Build, though.
Liliana's Standard Bearer - Comboing off with Gravecrawler can definitely score us a ton of cards when this enters the battlefield. We can then discard anything key to our graveyard at the end of our turn. It's also a zombie, to boot! Definitely worth testing for the Zombie Build.
Elder Gargaroth - Just because this creature is amazing in a vacuum doesn't make it good for this deck, unfortunately.
Obsessive Stitcher - This card does it all. It loots, you can sacrifice it to reanimate a creature, and it only costs 3 mana to cast.
Kels, Fight Fixer - For just 1 we can sacrifice a creature (preferably a zombie token) to not only make Kels indestructible but to draw a card as well. Even then, I think might be too niche to warrant a slot in the deck.
I can definitely see that. The deck is one where it's very difficult to find cuts for and there's already an amazing card I want to find a slot for from Zendikar Rising (the plant skeleton) since it makes an infinite loop in the deck.
But now that the entire set is spoiled (I think) I'm going to start reviewing the set both for my "A Flight" series on my YouTube channel as well as for my primers both here and on MTGNexus.
Don't worry, it's definitely coming soon! I did finish them for my channel but specifically for Sidisi and my other primers I just haven't had the time to do because I've been swamped with work. Hopefully I can finish it by tomorrow or Tuesday!
Glasspool Mimic - Although it enters the battlefield as a copy of a creature only we control, it still costs 3 to cast so it's pretty good. It's also a land in a pinch. This is definitley worth considering since it can double our best nonlegendary creature on the battlefield while also potentially taking the spot of a land in the deck.
Agadeem's Awakening - Even though it's not a creature, being a modular double-faced card means that it can technically take up a land slot in the deck - especially since it has the potential of entering the battlefield untapped. It's an amazing reanimation spell if we have the mana to cast it, which shouldn't be a problem since the deck is running Gaea's Cradle and Cabal Coffers + Urborg, Tomb of Yawgmoth.
Drana, the Last Bloodchief - She has the potential of reanimating a nonlegendary creature during each of our combat steps but I feel like it's a bit slow and we also don't have any control of what our opponents are going to choose. So there's that to consider as well.
Nullpriest of Oblivion - A bit expensive as far as reanimation spells go, but 6 mana with no other drawback isn't that bad. It's also on a body which is a plus.
Ancient Greenwarden - It's quite the hulk at 5/7 with reach for just 6 mana. However, this not being a landfall deck means that it's finally ability is pretty moot here. If I wanted to play lands from my graveyard with this deck I'd go with Ramunap Excavator instead.
Nissa of Shadowed Boughs - It's a great way to untap lands for additional value like Cabal Coffers, Gaea's Cradle, etc. On top of that, she can also be used to reanimate creatures or cheat them onto the battlefield from our hand. Definitely worth considering.
Here's my review for The Walking Dead × Secret Lair:
While no doubt a very controversial product, I do not believe in gatekeeping; I will still respect players excited by and looking forward to playing with these cards. Likewise, I respect those who took personal offense by this product. That being said, I will be objective in reviewing what could be used from this product for this deck.
Lucille - While the deck doesn't really use equipment, it does provide a slight buff as well as menace, which could be useful. More important than that, it has a trigger on attack which makes the defending player sacrifice a creature - making Sidisi even harder to block. If they sacrifice a creature, you get a zombie, which is also synergistic for the deck. This has the potential of finding a slot in the Zombie Build.
Michonne, Ruthless Survivor - She creates two 2/2 zombies when she enters the battlefield. However, the deck isn't really running equipment to make the most of Michonne's ability. Curiously enough, Lucille is an excellent equipment for a Michonne deck.
Hullbreacher - One of the new "boogeymen" to the format, while it can be included to steal opponents' draws, the deck isn't really forcing players to draw and it's hard enough to make cuts for it. Same goes for the next card.
Opposition Agent - The other new "boogeyman" to the format, while it can be included to steal opponents' ramp effects or tutors, the deck is more proactive than reactive. With how difficult it is to make cuts, it's honestly not worth a slot here.
Laboratory Drudge - While the deck obviously plays with the graveyard, the effects is too lackluster to warrant a slot.
Sakashima of a Thousand Faces - Another amazing clone that can copy legends, having another Sidisi could do a lot. While I wouldn't necessarily make a cut for it, it's still definitely a great card to add if you like these effects.
Tormod, the Desecrator - Another way to make zombies especially since the deck is getting things out of the graveyard. However, it's much more efficient making zombies with Sidisi than it would be with Tormod.
Kodama of the East Tree - Each time we create a zombie we're able to drop a land from our hand. Also, whenever we reanimate anything we can play a card with the same or lower casting cost for free. While I have yet to test it, this card has the potential to make some busted plays and should definitely be considered.
Araumi of the Dead Tide - With the graveyard full of cards, giving encore to a creature is a great way to reanimate them. However, the creature has to be exiled for its effect, which is something I've been very adamant on the deck not doing.
Aesi, Tyrant of Gyre Strait - While not a landfall deck, being able to play an additional land and being able to draw a card off of it is definitely something to consider.
Reflections of Littjara - Amazing for the Zombie Build. Everytime we cast a zombie spell it gets copied. Copying each zombie lord in the deck will go a long way very quickly.
Burning-Rune Demon - Is almost like a Final Parting on a body except that an opponent chooses which card goes to the graveyard and which goes to your hand. You also have to reveal the cards. However, we can make a choice that's beneficial for us regardless of the outcome since we like having things in our graveyard anyways.
Dream Devourer - For just 1B, we have a creature that essentially reduces the casting of our nonland cards without fortell (which is so far none of them). We can then recast them later on. So while we end up paying the same cost in the end, we can empty our hand if necessary and then cast the spells for cheaper when we can.
Haunting Voyage - Amazing for the Zombie Build. Its foretold cost is a bit high at 7 mana but it can reanimate all of our zombies which is no small feat.
Varragoth, Bloodsky Sire - A recurrable tutor on a body is no joke, especially when it topdecks what we're looking for. We'd rather have the card in our graveyard than our hand anyways. What's great about boast is that we can activate it in response to Sidisi's attack trigger. We can then have Varragoth's ability resolve first, topdecking something spicy for Sidisi to mill when her trigger resolves.
Roots of Wisdom - Believe it or not this card is kind of useful in the deck as it is. Currently there are 7 elves in the deck. Add to that 35 lands and there're 42 potential cards that this can return besides milling us for three.
Jorn, God of Winter / Kaldring, the Rimestaff - If your deck runs a lot of snow lands then you might consider playing Jorn to untap your lands or Kaldring in order to play them from the graveyard. However, my deck doesn't run a lot of snow permanents so it's not for me.
King Narfi's Betrayal - Not only does this mill the entire table for 4 but it exiles a creature of planeswalker from each graveyard. We can can then cast them afterwards for any mana. This is more helpful to us but at the same time we can potentially steal an amazing creature or planeswalker from an opponent. Definitely worth considering.
Narfi, Betrayer King - A bit overcosted at 5 mana but it is a zombie lord that can reanimate itself for SSS. Unfortunately, as it is, the deck can at most run 3 snow-covered basic lands. You'd need to include more source of snow mana to make it worthwhile to include.
The Three Seasons - Definitely worth considering for the Budget Build since it self-mills for 3 and then can potentially recover 3 snow permanents to our hand and then shuffle back 3 cards we don't want to remain in our graveyard.
Maskwood Nexus - Worth considering for the Zombie Build since it'll make all of our creatures zombies (as well as other creature types). It's cheaper than Conspiracy but not cheaper than Arcane Adaptation. It's also more susceptible to removal than Arcane Adaptation. That being said, for 3 mana and tapping it can create a 2/2 zombie for what the decks cares for.
Pact of the Serpent - As I've mentioned quite extensively, the deck doesn't really want to draw so much as self-mill. That being said, if you prefer drawing, then this card can definitely be considered for the Zombie Build.
Curate - Definitely worth considering for the budget build due to its malleability, speed, and casting cost.
Oriq Loremage - Oh boy, is this card amazing here! Not only does it trigger Sidisi if we entomb a creature, but this is a recurrable way to entomb an eldrazi titan for whenever we need to save our library. So not only can it always get us what we want to reanimate, but it can be used defensively as well. Definitely an auto-include!
Professor Onyx - Unfortunately, we can't make the most out of her magecraft ability. That being said, her +1 it is a good way to filter draws and self-mill; her -3 has all opponent sacrifice their strongest creature just in case; the last one wouldn't really be the point of running her, but her middle two abilities are definitely amazing.
Augmenter Pugilist / Echoing Equation - The sorcery side is the one that would be most fitting for the deck. Being able to make each other creature into a copy of Sidisi means that the amount of zombie tokens we create when we self-mill is ridiculous. Since the front face of this card is a creature, it counts as a creature for all effects and purposes for self-milling which is a huge plus.
Blex, Vexing Pest / Search for Blex - The sorcery side is the best side for this deck. You get to filter for any number of cards from the top 5 and then self-mill the rest. This is definitely an amazing spell for the deck, especially since the first side is a creature, making the card a creature card for self-milling purposes.
Witherbloom Command - While an amazing command, the modes best chosen are the first two. Naturally we want to self-mill so if there are no viable targets for the other abilities, just self-mill with the last ability.
Here are the most recent changes I've made to the deck. There will definitely be some more changes once I test a couple of Strixhaven cards when they come out. But for the moment, here's the current list for the deck: