Gol ding it!!! Forgot a few suggestions. Here they are.

Reanimate (mentioned it in comment #2 but forgot to list in comment #3 which is the actual list of suggestions)

Archdruid's Charm*** (can't recommend this enough. It's removal. It's a tutor. It's ramp. It can get any land in the game at instant speed. Very important for getting Glacial ChasmGC consistently and at the exact right moment)

Sowing Mycospawn (You run enough colorless sources to be able use its land destruction ability. It main purpose will be to increase your critical mass of any-land-in-the-game tutors and you don't even need to worry about having colorless for that.

If you add mycospawn and archdruid's along with expedition map while not cutting world map, you'll have a whopping 9 cards capable of getting any land in the game. You've got 6 atm. Definitely add archdruid's if nothing else.

Last post here. This will be a list of suggestions. If I place an "***" next to one I strongly reccomend you try to find room for it. Regardless, all of these suggestions should be considered as I think they're all good. I wouldn't be suggesting them otherwise.

LANDS

MDFC's:

Bala Ged Recovery  ^Flip

Agadeem's Awakening  ^Flip

Turntimber Symbiosis  ^Flip

Fell the Profane  ^Flip*** (highly suggest cutting a basic swamp)

Disciple of Freyalise  ^Flip

Branchloft Pathway  ^Flip (swap with a basic if you get this)

Brightclimb Pathway  ^Flip (swap with a basic if you get this)

Darkbore Pathway  ^Flip (swap with a basic if you get this)

Normal lands:

Thespian's Stage

Wasteland*** (I suggested this as a swap actually but I wanna relist it here so you don't forget)

Dust Bowl*** (Strip mine, wasteland, and dust bowl are the best lands that kill lands in the game, period. Run these 3 and you do not need any others.

Path of Ancestry (3+ color decks are gonna want any-color lands. You'd be surprised)

Mana Confluence (3+ color decks are gonna want any-color lands. You'd be surprised)

City of Brass (3+ color decks are gonna want any-color lands. You'd be surprised)

Horizon of Progress*** (3+ color decks are gonna want any-color lands. You'd be suprised) (The reason I added asterisks here and not the other 5 color lands is its ramp ability. You are running 40 lands so that ability will do work AND it's sac/draw ability will also be nuts in your deck. Did I mention it also taps for all 5 colors AND colorless too? Lol such a good land for you and in general)

Glacial ChasmGC***

Underground Mortuary*** (helps with graveyard, is fetchable)

Lush Portico*** (helps with graveyard, is fetchable)

Shadowy Backstreet*** (helps with graveyard, is fetchable)

CREATURES

(You want several more "play additional land'' effects in this deck. Believe me the deck will be way more powerful with a critical mass of these effects.)

Ancient Greenwarden

Dryad of the Ilysian Grove***

Traveling Chocobo

Wayward Swordtooth***

The Gitrog Monster

ENCHANTMENTS

NecropotenceGC***

Attrition*** (you have tokens out the wazoo to sac. this is also repeatable, reusable removal on a stick. even if your opponent has black creatures, its still a sac outlet.)

Grave Pact (double value if you have this AND attrition out. I would've put asterisks here too, but idk if you have enough sac outlets. Its good without sac outlets obviously, but with more it would be an auto-inlcude as opposed to a very solid suggestion)

Survival of the FittestGC (would've put asterisks here too but you need roughly 25+ creatures before this is really worth running. This appears to be the case with most cedh decks that run this and it's also been my personal experience. This is a suggestion that you could include or ignore tbh.

ARTIFACTS

(RUN BOTH OF THESE!!! VERY IMPORTANT)

Conduit of Worlds*** (also gives you general recursion for every card in your deck except instants and sorceries)

Crucible of Worlds***

SORCERIES

Ravages of War****** (extra asterisks lol. This is a functional reprint of Armageddon. Doubles your chances of MLD!)

INSTANTS

Teferi's ProtectionGC (reason for this suggestion is it's heroic intervention #2 for the purposes of comboing with Armageddon/ravages of war. You'll destroy all lands on the board except your own. Be prepared for people to ragequit lmao.)

CREATURES:

I like every single creature with the sole exception of the Ancient Adamantoise. Glacial ChasmGC does the same thing but way better and is more on theme for the deck. Also, swapping an 8 drop for a 0 drop MASSIVELY reduces the deck's average cmc. I'd simply cut this. You need to cut two cards regardless AND you'll probably want to make more cuts so that you can add in some of my other upcoming suggestions. These suggestions will be different than my "swap" recommendations in my previous comment.

LANDS:

You are running two of the three karoo lands (Golgari RotFarm, Selesnya Sanctuary) in your colors. I'd reduce this to one. Normally I'd never run any of these cards except in VERY specific decks. That said, necrobloom is one such deck that I would run these in, but I would only run one. These are even slower than a normal tap land and are brutal to have destroyed by a strip mine or something. But in a deck that can recur lands and play more than one per turn, they are worth including one of. Pick one of these and cut the other. You are running 11 basics in a 3 color deck which is pretty high. In order to justify running things like Cultivate and Kodama's Reach you'll only need about 6-7 basics. I speak from experience. Even if you wanna run more than 7, 11 is really high. And again, I will be suggesting a bunch of lands to include, so you'll wanna cut some basics and a karoo anyway.

Last thing regarding lands: your land count of 40 is actually a good number. Normally 40 is way to high, but this is a "lands matter" deck so 40 is a good call here. You could probably get away with 38 or 39 too, but don't worry about that unless you are desperate for cuts.

SORCERIES:

These are all very good except for two. I'd cut Regrowth. If you still want this effect (you already have Eternal Witness) then run Bala Ged Recovery  ^Flip. It's an MDFC land so it's awesome and synergies further with your deck. I'd also cut Dread Return. This card is actually VERY good and even saw some cEDH play when Flash/Hulk was still around. The flashback cost is also really good fro your deck. However, the initial cost of 4 is too slow. Consider Reanimate. This is the best reanimation spell in the game and this card is the reason reanimator decks are called reanimator. Also, with reanimate, you lower your deck's CMC more AND you can grab opponents' creatures with it.

INSTANTS:

I already recommended swapping Overkill for Swords to Plowshares. Other than that, I'd cut Reprieve. It's not terribly great (I know you want a pseudo counterspell, but this is meh). Cut it for NecropotenceGC and that way you still preserve and actually upgrade the card draw in the deck.

ARTIFACTS:

As mentioned before, you should still try to keep world map if you can. Endstone should be cut. It's VERY powerful, but it's both expensive and risky. NecropotenceGC is much better for drawing cards.

ENCHANTMENTS:

I like every single one of these with the sole exception of Spelunking. Sure it ramps you once (can wiff although VERY unlikely in your deck) but its 3 mana and theres a ton of two mana ramp you can run that's land based. Also you run 0 caves. The entering untapped IS nice, but swapping this card entirely for another card that let's you play more than one land per turn is going to be much stronger and also kinda negates the tapped lands as you're gonna be able to get more out which negates the slowness to an extent.

Swap these cards:

Demolition Field for Wasteland

Fabled Passage for Prismatic Vista (The true fetchland equivalent for basics)

Overkill for Swords to Plowshares (This swap will also lower your deck's avgerage cmc!)

World Map for Expedition Map (I'd still try to keep world map too but if you can only have one or the other, expedition map is superior)

Wrath of God for Damn (strictly better and more versatile) (I would still try to also include wrath of god but if you can only pick one, damn is better)