That sounds p cool. There's probably a way to proliferate Kaya to 5 loyalty on the same turn that you drop her and ult the opponent for 20.
This is what I'm running currently, but this is also messy because I'm still experimenting and trying the new cards, I'm limited by what cards I own (I absolutely would run more than one Kaya if I had 'em), and this is probably the second revision of the deck where I only did some super slight tweaking.
The 4 walls, fairly solid. The mill isn't completely insignificant and they usually safe you some life and/or protect your walkers. They still are PROBABLY unnecessary but I like mill so I dunno.
The negates probably should be more vetos, they're a bit easier to cast but eh.
Azcanta because it's Azcanta.
Veto since it's a nice counter and almost never a brick.
Despark sounded really good but it hasn't been as widely useful as I would've hoped. The contempts could probably be desparks but I haven't crafted more desparks yet.
Prison realm, wanted to try it. It's not the worst thing in the world but you'd probably be better off with Kaya's wraths instead, especially if you're running the walls to help protect your ass early game.
Baby Teferi is sort of cool but after playing with him a bit it feels like he either needs to be a 2 or 3-of or relegated to the sideboard to help protect you against control. In this deck in particular casting sorceries at instant speed isn't super relevant so he's on the chopping block for me right now, just haven't adjusted the deck more.
Absorbs, more counters.
Kaya, all around great. 1-drop removal, potential life gain, and bigass finisher if she reaches ult since Ashiok's dumpstering their library at a rapid rate. She'd be a great 2-3 of especially in place of baby Teferi.
Mortify, removal and enchantment hate.
Ashiok, 3 of him seems pretty good. You're going for a "Slow mill" rather than trying to race, so plonking him down every once in a while as you protect him and get maybe 1-2 activations before he's removed is the general idea. He combos great with Kaya too of course, but blasting someone for 20+ damage with Kaya isn't your only win condition since with the walls and Ashiok you're removing not insignificant numbers of cards from their deck.
Ixalan's binding, more being a big asshole. It's actually a little less vital given you'll be binning a lot of your opponent's cards anyway, so cockblocking with binding isn't 100% critical, but it's still useful to have.
Chemister's insight, help keep you stocked up on counters/removals. Might be excessive running 4 of them but it helps so fucking much.
Vraska's contempt, as mentioned despark might be a decent alternative.
Cleansing nova, probably going to get trashed in favor of another time wipe or a Kaya's wrath or something else. Stuck it in when I was throwing cards together and never got around to removing it since the enchantment removal's a bad idea with the binding cards.
Teferi, 'cause I've got one of them and he's completely busted. Probably could stand running more of them. Immortal sun wouldn't be a bad alternative either.
Time wipe, as mentioned it's an expensive sweeper that you can use to pick up a wall so you can play it again. It's PROBABLY more cute than good and you'd be better off with Kaya's wrath/ritual of soot/whatever, but again it's playing with the new cards to a degree.
I think flux channeler would probably be worse overall. You could potentially hit the dream combo faster but I think you could more reliably get there by going slower and more controlling. Elderspell would probably be a slightly better option simply because you could throw a Kaya down, kill your own existing Ashiok you've been downticking with elderspell to boost Kaya to 5, then fire the Kaya laser. And elderspell would give you the advantage of controlling opposing planeswalkers too so it feels a little more flexible than flux channeler for this kinda memery.