A Myconid colony (ganked the OG Dungeons of the Slave Lords mushroom-men) inhabits a hive-like series of caverns deep in the dungeon complex. Reclusive and contemplative, they distrust outsiders, avoiding them and considering them to be disruptive, if not downright destructive. There will be 25 individuals present - 5 'circles' with one each of 1 to 5 HD, plus a 'Sovereign' (6HD). If the leader is killed or dies, the strongest of the 5HD fungus-men will replace it.
In addition to their native spore-generating powers, these myconids recruit mycelium to communicate and amplify their powers. 2-5 fungoids will touch and meld via the mycelium fibers over a period of 10 rounds (1 minute). The group's composite HD will allow them to release higher-level spores (up to 5HD equivalent), and penalize saves by 1 point for each fungoid in the collective.
The entrance is 'guarded' by pet slime-molds - the slimes are attuned to the myconids,and will not attack them. Intruders will be attacked be slimes dropping upon them (2 brown slimes, HD 2+1, AC 9, Move 0 (drops), attack clings to victim and turns to slime in 1d4 rounds, immunities: acid/electricity, 1/2 damage from fire). There will also be 2d4 fungal zombies of 1/2 to 2 HD in the colony at any time.
The walls of the colony are luminescent with fungus, and the colony has several chambers. The 'circles' inhabit the outer chambers, and the central chambers are used for their fungus garden. Many varieties are grown here, most benign, some beneficial, some hazardous:
a) Purple gnome-cap – Highly poisonous (Save or die if ingested). Dried and powdered gnome-cap is used by discerning poisoners;
b) Red Antler – strong hallucinogen lasting 1d4 turns, Save or: 1-2 - catatonic, 3-6 - helpless giggling, 7-9 - violent rage, 10-11 - blinded (1 day), 12 – prescient vision (1-3 days in future);
c) Yellow-ribbed morel – Delicious, nutty flavor, and high in calories. Nicknamed 'cave-pemmican';
d) Stinky pixie-seat – Odorous shelf fungus. Save or nausea 1d4 turns;
e) Blackcap – black, withered mushroom. Cures 1d6 HP upon ingestion;
f) Orc-dong – purplish-green, quite phallic. Fresh and dried specimens bring high prices among epicures.
g) Braveheart toadstool - +2 morale, dying blow – 1 final attack roll upon reaching 0 HP, regardless of turn.
(borrowed these from my myconid colony: Variation 1, here)
The Sovereign lives alone in the smallest chamber. There will be 1d4+1 potions available at any time (pick 1st-3rd level magic-user potions and/or 1st-2nd level divine potions).
The mushroom-men are not interested in trade, but may parlay a few mushrooms or potions to an appropriately amiable individual or group. They are more likely to retreat and rely on their slimes and zombies to keep intruders at bay.