Things to keep in mind:

Being Birthing Pod on a stick, it will be assumed your commander is on a high value/combo win game plan pretty much regardless of what you build. I see her as the type to "accidentally go infinite" myself. This will mean she is going to be targeted by counter spells and instant speed removal, or really any strategy that is already being used against Yisan, the Wanderer Bard. While you have blue, and therefore counterspell options ad infinitum, I recommend the good ol' "boots and greaves" package.

Secondly, I see no reason to run zero cmc creatures. Tokens can get the job done if you really want to work from the bottom of the barrel up, and there are plenty of cards that can fill that role without being dead draws in a stalled game. By all rights, if you're playing Vannifar onto a board without fodder already, I think something is horribly wrong.

I'm not sure what else to offer for card suggestions/insights as I'm not used to playing competitive magic like what you're starting with here (I mean, you're playing zero cmc ramp spells and force of will, which is basically equals top tier imo). My own playgroup tends to hate on players that try to win within the first 5 turns, so my advice is going to be biased towards more casual play. Or else I can just be truly unhelpful and simply point out really "out there" strategies or niche effect cards. Like Magewright's Stone. Also, Vannifar doesn't care if the creature being sacked wasn't a creature a moment ago like in the case of Haunted Plate Mail.

TheRedGoat The problem we see with greaves is that shroud conflicts with our untappers when we want to target Vannifar. Boots may earn a slot, but we are in the process of narrowing the focus of the list and making necessary cuts as this is only a first draft. As far as the 0-drops go, they are slotted in here primarily to combo off with Protean Hulk when we sac it. Our Hulk package consists of Ezuri, Claw of Progress, Sage of Hours, and the 0-drops to put them into play and get experience counters with them, and then place counters on Sage each turn to assemble an infinite turn combo. Also, this deck is really out there right now so don't think your more niche suggestions are unhelpful just because they're out there! I always encourage creativity and thinking outside the box. Magewright's Stone is good for an untapper, and we will definitely take it into consideration, but Thousand-Year Elixir somewhat outclasses it for being a sort of haste enabler for one extra mana. Haunted Plate Mail doesn't feel the greatest in Simic colors because we don't have the best artifact tutors available and we wouldn't be able to tutor for that in our pod lines.

For the greaves I see where they are an issue for "ETB untapping" creatures and I hadn't considered how many you run. I also didn't catch the zero cmc creatures being there for the combo, but at that point I feel you're reaching pretty far for a combo that would be easier to assemble with basic creature tutors. At least on paper it sounds that way. In practice it might be rather easy. I wouldn't know myself.

Real suggestions I feel would be involving Seedborn Muse or Quest for Renewal or Intellectual Offering and a similarly large volley of cards that ultimately would warp into a deck of it own. I don't enjoy hearing that so I'm not about to go on about it really.

As far as the niche cards, things like Instill Energy or say Crab Umbra line up better with my train of thought, and the plate mail was representative of its type of effect more than being a suggestion itself. With the speed you're wanting to play at, "non-creatures to creatures" would always be too slow, but the idea is to have something that is harder to remove and still be working towards your combo. I'm certain there are better examples but it is late and I'm not firing on all cylinders atm.

In any case, gl with your build. I might have my own take on Judith, the Scourge Diva up by tomorrow night at the latest and I'd love your insights on it.

With Retreat to Coralhelm in play you could use mana tutoring dorks and make a chain like like Veteran Explorer > Viridian Emissary / Primal Druid > Farhaven Elf / Wood Elves > Wild Wanderer / Solemn Simulacrum > Gobbling Ooze > Ulvenwald Hydra > Protean Hulk. You should have mana left over and a sac outlet to use on the hulk at the end of it. Even if you get fizzled somehow you ramp out a bunch of mana in the process. Imagine it happening with Amulet of Vigor or Lotus Cobra in play too...mmmmm yummy over kill.

Could be an interesting angle to explore for the deck. However it since it requires the enchantment to be in play to function, we need ways to find it. I think the best tutor for it might be Drift of Phantasms... which also conveniently finds Intruder Alarm and Faces of the Past (which probably enables some decent elf/wizard/ooze chains too). Getting the Drift of Phantasms in hand should be easy enough with all the creature tutors available in green. Could be cool, maybe even good ;)

TheRedGoat My favorite part of this deck is that we aren't reliant on Vannifar at all. Unfortunately our current untap chain (havent looked at the one suggested by Rzepkanut yet) gets us to Protean Hulk without a way to sacrifice it, BUT odds are we have an extra untapper in hand or possibly High Market. We can also use Vannifar to bait counterspells if we're holding either half of Flash + Protean Hulk, and Defense of the Heart can also grab Ezuri, Claw of Progress + Sage of Hours. The creatures involved in these lines may change but the lines will always be there, which makes us pretty resilient to hate.

Rzepkanut, unfortunately that chain doesn't work because we won't have a sac outlet at the end, which defeats any upside of adding such radical changes to the deck imo. You have to sacrifice Gobbling Ooze to continue the chain.

I see you're going for the ezuri turns hulk. What makes you believe that it's more efficient than Pili-Pala, Grand Architect, Walking Ballista, Rootwater Diver?

Never heard of that one, thanks lol

It's just fewer cards - so you have more flex-slots and fewer do-nothing cards... Hit up my vannifar list - it's pretty similar to yours, though I'm thinking of changing out some pieces to make it food chain. Vannifar-cEDH

CyborgAeon we just realized that Rootwater Diver does not have haste in this line.

Yeah. That's the only flaw with it... but it still offers the same result in a vacuum. Conversely there may be other lines available - I just see the 6 card ezuri one being quite dead and requires more precise draws. Infinite turns from 2 mana flash hulk isn't bad though.

The Ezuri one isn't dead because we can cast any 0 cost that we draw for the same result, and they give us a creature to start chaining from. Killing in the same turn is essential for Hulk.

Sure - you're right there. After you hulk, all the 0-drops in hand do something. But you don't feel that there's got to be a better hulk pile? 6 cards is a lot.

What about: Hulk > volrath's shapeshifter, phyrexian dreadnought, phantasmal image > peregrine drake, deadeye navigator + any 1 mana outlet. The outlet doesn't even need haste, since you can flicker all of these with infinite mana and deadeye navigator for protection. Options for slot:

1: use artificer's assistant, cast vannifar, flicker deadeye - pair with vannifar, exile vannifar to deadeye, replace with the command zone so she doesn't return. Repeat to tutor any card to top of library

2: use drowner initiate, cast vannifar, flicker deadeye - pair with vannifar, exile vannifar to deadeye - replace with the command zone so she doesn't return. Repeat to mill your opponents to death (if they are jammy and use an eldrazi, then just repeat'til they have 0 cards in library save for that titan)

3: Nothing. Just play out everything in your hand & vannifar, then use your removal-proof board state to stay protected. For additional protection you can also cast sidisi's faithful from your hand again, and choose not to exploit - so that if by some miracle they do have a way that beats this combo, you can save a piece by flickering the faithful, exploit the dreadnought and bounce the combo piece for protection.

Now you might be thinking, all that extra work for the same number of cards? Not if you go with option 3. Furthermore, these creatures do something a little more than the application of the 0 drops (in my opinion... though gaining infinite turns might be worth the extra slot, instead of this).

I do not want a Vannifar reliant hulk pile

The point is a pile that wins the game on the turn it comes in on its own. Ezuri is the most efficient Hulk pile that wins the game in Simic.

That Ezuri + Sage of Hours infinite turns line is spicy! +1