And here's the final document: Walled Mound of the Hive Caller
I had mentioned in the last part that I was going to add a roster instead of leaving the monsters in keyed descriptions, but once I started doing that, it felt like I was ending up with too large of a roster to be advantageous in actual play, so I nixed that idea and stuck with the original presentation.
Working with base material from older editions (OD&D in this case, albeit modified per OED) can lead to some interesting discoveries. Given that the "clean-up crew" of oozes, slimes, jellies, and mold originated in OD&D Vol 2, I was completely surprised that what I'm used to as classic fungus monsters (shriekers and violet fungi) seem to have not shown up until AD&D's Monster Manual, and neither appeared in Basic/Expert D&D, either. It wasn't a huge problem to stat them out, of course, but it caught me off guard.
Speaking of statting out monsters, I somehow overlooked doing anything for the hanging moss in the last part, but I pretty much treated it as a levitating green slime with spore infection instead of transforming victims into more slime. Delta's OED monster database is rather unhelpful in giving green slime an EHD of "?", but I'm just saying that to tease him; in practice, it's more of a trap than a monster.
Frankly, I'm not entirely happy with the details for the hive caller. The engineer in me wants it to have more rigorous definition and structure, while the artist in me wants it to be more mysterious and evocative. Ultimately, I think I ended up with enough to act as an inspirational springboard in actual play, but I feel like this is something where I would've benefited from having other people to help hammer out what it needs and what works better if left vague.
Other people would also be great for playtesting the whole thing, of course, but I digress.
My off-the-cuff mechanics for iron poisoning, lead poisoning, and tetanus are probably less deadly than the actual conditions, even with some little adjustments from the original drafts in Part 4. I suppose I can accept that adventurers are somewhat hardier than common folk, diseases are meant to be complications rather than focal points, and something that has an impact which can be worked around via player ingenuity (and lucky saving throws) is better than a strict representation of the actual conditions. None of it is likely to come up unless the players make a habit of eating weird fungi or rummaging through metal scraps without using tools, anyway, so I'm not too hung up on them.
On the note of weird fungi, I have to give credit to The Dragon's Flagon blog's Fantasy Fungi post for inspiring a number of the additions I used for dungeon dressing. I didn't reference it while writing up the key entries because I wanted to allow some freedom for gaps in my memories to inspire creativity, but I had read it recently enough that I probably ended up with details very close to that post's, if not exactly the same.
Since most of the dungeon was a termite nest, my typical dungeon dressing detail tables were of little direct use. I ended up rolling on Table 3-47 and Table 3-48 from the Tome of Adventure Design for names of areas involving bugs and plants, respectively, and relied on my own imagination to translate those names into actual details (though, in retrospect, going a few pages further to Table 3-70 for unusual plant details would've been a reasonable supplementary option). All of the notes about floor/ceiling height, humidity, air currents, smells, sounds, and condensation were my own inventions, based on my understandings of fluid dynamics and industrial ventilation (though I was on the liberal side with these since I wasn't mapping every last crack and crevice), imaginings of what termites might find useful, knowledge of the surrounding rooms, and the occasional flights of fancy. Using random tables for those instead of what's sensible from context is a peeve of mine, since unless you're designing a illusionist's castle or the like, I think those environmental flourishes work best when they serve to either foreshadow what's to come or reinforce other elements of the environment. Coincidentally, Justin Alexander had a recent series of tweets that included complaining about misuse of such details in Descent Into Avernus, in part because his group includes players who'd pay attention to them (although in WotC's defense, the snippet that Alexander quoted calls out "flammable gas", which isn't necessarily methane-based natural gas and could just as easily be hydrogen sulfide or sulfur dioxide).
For the ruined building rooms within the nest, I used the tables on page 4 of -C's Tricks, Empty Rooms, & Basic Trap Design to get ideas for what the rooms used to be and ran with it from there. This resulted in some of wonderful items: "crypt, animal" for 5 and "guardroom" for 22. 5 strikes me as turning out especially great, since it's a weird and unexpected thing that has nothing to do with the adventure at hand but prompts the prospective GM to invent something about the culture of the people who'd lived there to explain it.
Tidying up the maps and getting them to fit the document while still being legible took longer than expected, and then I needed a while long to shave down the last bit of text to fit that disease table on the final page. In any case, I was pretty satisfied with getting a roughly 50-room dungeon, complete with monster stats, on just four pages. I'm sure there are places where I still used more words than I had to, but I think that's always going to happen when editing your own work. No background or rumors in the final draft, since the site is strange enough in and of itself that I'd rather leave it up to the prospective GM to decide how everything fits together and what other people might know (or think they know) about it than imposing my thoughts. Likewise for omitting details about other obvious questions like how much time it takes the workers to modify the nest's geometry in response to intrusions or whether any of the dangerous fungi can be used to poison either the termites or the various intruders.
Overall, I'm very happy to have gone through this process, and I'm excited to put the end result into actual play (so I'm belatedly hoping nobody who plays with me has actually been reading this series)! It's probably too big to do the whole thing in a single 4-hour or so session, but I could see it serving either as a campaign-starter in place of something like B1 or B3 (assuming you want a campaign about creepy fey and/or moss cultists), as a stand-alone site for a hex crawl (throwing it on one of the little satellite villages in Better Than Any Man as an insect-themed dungeon completely unrelated to what's going on in that adventure [or is it?] sounds like a delightful idea), or as a tournament challenge to do as much as possible in a single sitting (with an added scoring system, perhaps rewarding treasure found and resolving the agendas of the faerie and/or moss while punishing deaths and diseases).
If anyone out there runs this or even just uses it as inspiration for your own dungeon design, please let me know how it works out for you!