Here are the cuts I'll be making once the new cards come in.
Mostly they're straight swaps for better/more appropriate cards.
Cut Your Losses is always 6 mana, and requires a sacrifice to hit the same target twice, or a second target, whereas Cacophony just hits everyone for the same mana cost, and has an alternate mode of milling 8. Seems better.
Some of my creatures dodge Languish, but not all the valuable ones, and it won't necessarily hit what I want it to on opposing boards. MAE hits what I need it to, and may hit some other stuff as well. Will see if it works the way I want it to.
Windfall is super good, but I've found that the deck doesn't have the sorts of interaction to mitigate refueling 3 other players. A couple times now I've wheeled and gotten punished for it. Also, with the highish CMC of the deck, I'm not always in a position where I want to dump my hand for new cards. Rhystic should be just straight value, and with my draw=mill, may teach some players to pay their taxes. It IS tempting to keep this alongside the draw=mill enchantments, and especially as a way to force draws on empty libraries, rather than waiting, but for now it's out.
Endless Evil looks like a fun card, but I've had it in hand a few times and never cast it. It does nothing for a turn cycle, is open to removal, and even though it may return to hand, that's still not great. And I don't feel like I have quite enough worthwhile ETB/attack/damage triggers on creatures to make 1/1 copies especially valuable. Court of Cunning may make me a target, and may give other plays draw, but it will draw me at least one card, and can provide a LOT of mill.
Wrexial comes out for not being a horror and for being expensive to cast. It could come back in at some point, but the top of the deck is pretty clunky. Harvester is less expensive, and comes with two forms of interaction stapled to it. We'll see how often it puts in work, but especially being able to turn off commanders can be very relevant (see:
Ixidron).
Grell Philosopher comes out because it just hasn't really done much so far. I've had one instance where it allowed two of my horrors to tap for mana, and the dream, I guess, is to copy a Sol Ring or Gilded Lotus or something, but I don't have many cheap horrors, and tapping the big guys for some mana feels bad. I'm struggling to think of other artifact activated abilities that I want to copy and would see consistently enough to keep this. Otherwise, it's a 1 power horror without native evasion. I had considered cutting Thief in this slot, since it's not a horror, but realized that as far as tribal synergy goes, the two main reasons to run horrors are for the mill and menace granted by the Captain. Well, Thief has flying, which is better, and already mills 2 and steals a card. I've also been wanting to run it in a deck for a looooong time, and it actually fits here, so it stays in for now. It also double-mills if Maskwood shows up. Teferi's Tutelage is just providing more incidental mill, and comes with a little looting. The right play might be just replacing Psychic Corrosion with this, but will try both for a bit. Truthfully, this slot should probably be something like
Propaganda to ward off getting beaten down, more removal, or more card draw.
Elder Brain has been very meh so far. It's big and slow and enough of a threat that people want to remove it. Of the 3 times I've swung with it, I have gotten a hand full of land and a piece of ramp (not bad, but also not super relevant at that stage of the game), a handful of off-synergy tribal junk that didn't do much for me, and some decent stuff that didn't matter because that player was milled out from the attack (Elder Brain helped by forcing a draw of 5, but since it's on attack and not damage, they drew before milling, so it couldn't kill them anyway). Maskwood Nexus' main job is to turn creature I steal with the Captain into horrors so they can contribute to the game plan. I've had a few instances now where I've reanimated big, evasive creatures, and just kept them back as blockers (not terrible), because I knew I wasn't winning with combat damage and they didn't mill. I've also had a couple instances where I've stolen utility creatures for ETBs, and then they just sat around as chump blockers or junk, when they could have been doing more. With Kindred Discovery, this can be even more valuable. The added benefit of being able to sink excess mana into making bodies is just gravy.
Changeling Outcast I initially didn't want to drop, and was struggling for what to remove for the Crab, when I realized that Outcast is, at BEST, going to mill one player for 3 cards (assuming a +1/+1 counter AND lord effect), and maybe draw a card or two if my board is just POPPING, whereas Ruin Crab will mill 9 cards on one land drop. Even if I'm not hitting lands consistently, this does WAY more for the same price.
I really have liked Mind Funeral when I've played it, but if milling is what I want to be doing, Tasha's is going to be more impactful most of the time, even if it doesn't stock the yard for the Captain. If they were both single target, I wouldn't make the swap, but going from single target to everyone feels like the right play.