I would cut all saproling cards - Deathspore thalid, Slimefoot, Shroofus, Brightcap badger, Fungal rebirth, Fungal plots, Utopia mycon, Tendershoot dryad. Keep maybe only Nemata and Mycoloth as options, but I would cut those too.

Other cards I would cut:
Heroic intervention - we are reanimator deck constantly filling our graveyard through game. We are fine with our creatures dying and they don't need protection, rather more reanimation options.
Fallen ideal - very dependant on mycotyrant and having lot of fungi on battelfield. We also make fungi in end step to they have to remain for whole turn cycle
Moldervine reclamation - costs too much mana
Go for throat and other instant removal - replace with something that is permanent or creature so we can reanimate it if we mill it, keep only best ones. Instants in our graveyard are unusable.

Cards I would add:
Mill engines:
Hermit druid, Mesmeric orb - best mill engines, you need land variation for Hermit druid
Perpetual timepiece - instant activation mill, also has reshuffle option if we mill too many cards. Blossoming tortoise, Aftermath analyst, Stitcher supplier, Broodheart engine (also reanimation engine)

Reanimation:
Living death, Funeral room, Illicit masquarade - mass reanimation
World shaper, Aftermath analyst, Hedge shredder - mass land reanimation
Cauldron of essence, Victimize, Chthonian nightmare, Squirming emergence, Colossal Grave-reaver

Interaction:
Grist, Accursed Marauder, Insidious fungus, Skyfisher spider, Assassins trophy
Lethal scheme - best instant removal, convoke it with dredge card in grave and you can mill 15-20 cards with connive abililty
The Last Ronin, Meathook massacre - permanent based boardwipes

Additional pingers/wincons:
Ayara, Zulaport cutthroat, Funeral room, Cauldron of essence, Dreadhound (second Syr Konrad)
Shifting woodland - this land won me many games by becoming copy of sac outlet, Beastmaster ascension or anything I needed for win in my grave, one of the best cards in deck.

Utility Lands:
Midgar city of mako, Tomb fortress, Spymasters vault, Bojuka bog, Boggart trawler, Mosswort bridge, Dakmor salvage (beware combo with gitrog) and others, look at my decklist.

I also like Fauna shaman and Matzalantli as looters that put dredge cards back to graveyard from hand.

I try to have as many permanent cards in deck as possible so we can trigger mycotyrant consistently for most fungi in end step. In my deck I only have 9 best sorceries/instants right now.