To be honest, I'm not much of a fan of Ancient Craving or Ambition's Cost. They're nice to refuel after you play Vilis but otherwise aren't worth the cost imo. Falkenrath Aristocrat and Deathgreeter don't seem to have the support to be very impactful either, and I imagine you could use more rocks. Charcoal Diamond and Jet Medallion seem like good inclusions from your maybeboard. Speaking of, Lord of the Void and Twilight Prophet are also sweet cards that you might want to swap in; if you can get them to stick they're both terrific.

Thanks for the advice, ThoAlmighty!! This deck is one of my new decks built almost entirely out of cards on-hand. I bought the Venser's Journal, Gilded Lotus, and kind of bought the Torment of Hailfire and Exsanguinate for it and had the rest of the good (and bad) cards already in my collection in need of a home. As such, plenty of the card choices are not ideal or optimized. In a sense, this is a budget deck not looking for big-time upgrades yet. I'm aware that Deathgreeter and Falkenrath Noble don't synergize with my deck at all but they are just incidental lifegain and as early-game blockers. Definitely filler for now. Deathgreeter might have enough utility (in my meta) for his cost to stick around until I get something great for lifegain, such as Twilight Prophet or Exquisite Blood etc. I was thinking about replacing the noble with Ivory Tower since it's old and janky and one of those "works almost nowhere except this commander" cards. I want to play more games and see how important lifegain ends up being to me. Some decks run a shitload and some run almost none.

I've played five games now and in the three games where I played Ambition's Cost and/or Ancient Craving they have worked out. Ideally they smooth out my mid-game and draw me into more lands, ramp, and answers/removal to get up to Vilis. So far they have done so. I also don't have a ton of free-life-payment cards like Doom Whisperer so they serve as passable refueling for Vilis. More games will surely give me insight but for now I like them.

So far the ramp has worked out all right but I had an eye to add more already. I have twelve pieces (13 if you count Nykthos, Shrine to Nyx... oh to have a Cabal Coffers too!! Just gotta wait for Commander Legends). I usually have 7-10 in my decks so this is still feels like a good, high amount. I used to have Bubbling Muck and Dark Ritual in the ~105-card prototype but they were late cuts, reducing my overall ramp-card count without replacement. Five games isn't a huge sample size, to be sure, so I'm gonna feel it out some more before I make swaps. I would definitely add Thought Vessel as an early upgrade. I was also thinking of swapping the Leaden Myr for a mana rock that doesn't die to all my wraths.

Thanks again for your comments!