There are much easier ways and synergistic ways to get 2 black or green creatures than going through Gravecrawler. Namely some big ones are Rootwalla and Bridge from Below. Gravecrawler’s limitations was one of the reasons that Hermit-Vine hasn’t really ever been a thing. Paying 2-4 mana post Druid activation is quite a bit. Hogaak can cost you 0, and at most 2 (if you run acorn harvest). That’s a cost reduction of about 2 mana.
The two example builds in the original post run eight non-Gravecrawler Zombies, so I'm inclined to agree with that number.
I like a deck that can win without Hermit Druid, but still has three and an Anger to combo off if need be. Sometimes you'll want to go hard, sometimes Hermit Druid is just a creature cast for Vengevine or a green mana to cast Hogaak. I watched the live stream of Jarvis Yu getting this trophy and liked how not every win was an Altar win.
I can’t really test ideas or come up with a list because I’m so busy with school but based on my experience in the most recent challenge, don’t you want 4x Collector Ouphe no matter what? PO is nearly half the meta and they struggle against the Ouphe. Shops doesn’t like it either. I’m just saying this because I’m also even considering playing 4 Ouphe in BUG style blue control. It just seems that good right now.
I agree putting too many pieces into the Druid combo basket can leave you open to a lot of blowouts when you don’t draw it / it gets answered. Which is why I don’t view Crawler as a necessity. The deck will already have a number of GY based cards and likely needs to function as an effective hatebear/bazaar deck in addition to the GY shenanigans. It’s possible Crawler is still a decent choice, but feels like a win more with Hogaak in the deck as you already have to have an active yard + mana + a zombie in play for Crawler to function.
Here's my initial rough draft.
4 Stitcher's Supplier
3 Carrion Feeder
1 Putrid Imp
3 Hermit Druid
3 Hogaak, Arisen Necropolis
2 Collector Ouphe*
1 Demonic Tutor
4 Cabal Therapy
4 Bridge from Below
2 Altar of Dementia
1 Black Lotus
1 Mox Jet
1 Mox Emerald
2 Bloodstained Mire
3 Verdant Catacombs
4 Undiscovered Paradise
4 Bazaar of Baghdad
3 Veil of Summer
4 Leyline of the Void
2 Assassin's Trophy
2 Maelstrom Pulse
2 Collector Ouphe*
2 Seeds of Innocence
*: Numbers/card choices adjusted as needed.
(1) How do we win after we activate Hermit Druid?
-cast a Cabal Therapy via Hermit Druid to clear the way;
-Trigger Multiple Bridge from Below
-Convoke Hogaak, Arisen Necropolis twice
-Trigger Multiple Vengevine
-Trigger Multiple Bloodghast
-Alpha Strike (due to Anger)
(2) Is Altar of Dementia too cute? Do we just want to run the full set of Collector Ouphe in the main instead?
For the more "control" version, I had run this in a few leagues pre-restricted list change, and it felt alright. The combo requires a turn + a land drop after playing a 2CC 1/1 so you need a little bit of time usually against these decks, and playing these elements also gives you a few cheap wins when you opponents keeps a loose manabase. Which is why I suggest a more control version of the list than a glass cannon.
3 Hogaak. The whole reason this deck is possible now.
4 Hermit Druid+2 Forest. This usually gets you in a good Hogaak range, but not so far that it kills you.
4 Deathrite + 5 Wastelands+1 Chalice of the Void. This was a strong hedge against mirror matches, Dredge, Storm, and some of the other fast decks. Chalice also functions as anti-hate against Tormod's Crypt.
4 Ouphe. You are protecting a 1/1 against Walking Ballista so this is pretty important.
4 Bazaar + 1 Survival. This is a backup plan for when you don't have 2 mana on turn 1, or need to dig some later in the game. I think Survival, itself, is optimized as a singleton since it doesn't function well in multiples (not a land/mana source).
4 Hollow One+4 Rootwalla+4 Vengevine. We have Bazaar, and need green creatures for Hogaak so its good.
3 Bloodghast+Dryad Arbor. Just a little bit more help for getting to the 3 G/B creatures that are needed to trigger Vengevine off of 2 Hogaaks.
Fetch mana base. We need to get our Forests out sometimes to speed up, if we want to, and dryad arbor is there so we've made this decision already. Double trigger on Bloodghast can sometimes be relevant after they get Haste.
Blue lands+Ancestral+Walk. We are already a fetch mana base with only really green cards.
Sideboard. This is most designed for a little bit of extra Dredge hate, and cards to fight BUG fish.