After quite some internal deliberation, I've come down in favor of building this adventure as a nodal mystery. A dungeon crawl through a foundation built out of the bones of some ancient behemoth still sounds great and may be something I revisit at a later time, but for now, I'm more interested in an adventure that can fit into a city environment, since I feel like that meshes better with a secret cult that has a semi-informed general body and a special inner circle. Cults don't just spring up in random villages, after all, and setting it in a city provides some population base to draw on for members and ancillary support without needing too much thought on how the other people in the area feel about it.
So, to recap, there'll be five key locations in the city where the cult is operating. One (the starting point) has some illusion protecting records, canon, scripture, or something other bundle of information along those lines. That'll having some planned clues pointing to a place for material preparations and to a place for further indoctrination. Each of those will then have clues pointing to the other and to the two seats of the cult's power: a means of fantastic transportation and a reliquary stash intended to revive the cult's god-beast.
I'd been using "reanimate" before, but my hands just wrote out "revive" there, and that's given me a flash of inspiration: the curse of the "cursed monastery" is that they don't realize their ritual is incapable of actually reviving the god-beast. If they succeed, they'll just end up with a mindless force of destruction as inimical to the cult as it is to any other life rather than whatever they think they'll get.
Now, what to do about the middle part of the title: "monastery"? I could just ignore it as having served its purpose to inspire the adventure idea, or I could use a mundane monastery as one of the key locations, but neither of those feels particularly satisfying. Perhaps it's more figurative, referring not to an actual building but to a sort of malicious genius loci that makes completing the ritual possible, albeit with unintended results? Oh, maybe that's what'd inhabit the reanimated skeleton of the god-beast! And it can exert some degree of mental influence on the inner circle, hence explaining why the order is cursed instead of just mistaken about their ritual! Maybe the order, or at least its initiates, thinks that the tooth implanting is merely a ceremony, but the fossils actually act as conduits for the genius loci's will.
I rather love it when things tie together like that. This also opens up some opportunities for extra rewards for non-lethal approaches to conflict, since the inner circle members could presumably be freed from the influence by removing the implanted tooth.
That settled, I need ideas for the actual key locations so that I can figure out an initial incitement, at least some of the clues, and maybe some more details on the ritual's requirements and/or timeline. I could just roll on the "structure" column from Tables 1-1A/1-1B of the Tome of Adventure Design, but I want to mix in some other sources. Five rolls on the "purpose of area" column from Table 3-9 gives:
Closets, lockers, small storage
I used different labels from the nodes because I want to make collections of results that I can then place in whichever nodes I want. Thus, to add to the above, here are five rooms from the tables on page 4 of -C's Tricks, Empty Rooms, & Basic Trap Design:
I'm not entirely happy with these lists. How about also using the general dungeon chambers table from page 295 of the 5E Dungeon Master's Guide:
I'm tempted to find another source to roll on, but let me see what I can do with what I've got so far:
Armory + Antechamber + Shrine: The workshop of some master armorer, known for producing amazing ceremonial designs. Some say that their talent is a gift from the gods, and getting the latest of their works is a point of pride among various competing factions within the city. The armorer is targeted by the order for kidnapping, perhaps interrupting the PCs' attempt to retain the armorer's services or being in the process of kidnapping the armorer when the PCs arrive on the scene. The inner circle monk is carrying a booklet with information about the cult which is ensorcelled to look like a collection of hymns.
Chantry + Classroom + Guardroom: An amphitheater which often hosts performances for religious purposes. Beneath it is an induction center where initiates are held to endure tests of faith before the final surgical ritual to bring them into the inner circle.
Armory + Great Hall + Gallery: The estate of a noble known to be an art collector. They employ a select few personal artisans for commissioned work and restorations. The noble is an initiate of the order, and two of their artisans are also members who use the facilities for the order's purposes.
Arena + Morgue + Temple: A legitimate cemetery under ownership unrelated to the order, which contains a mausoleum used by the order. There is a hidden portal that can send people to some dangerous place, where the order collects materials for use in their reanimation ritual.
Closets/Lockers/Storage + Waiting Room + Dormitory: A hostel in the heart of the city, staffed and occupied by members of the order. The reliquary is stored in a room hidden by magical means and guarded by a monstrous golem.
That seems like a reasonable start to expand from. Matching them up with the node ideas from the previous post means my key locations are the master armorer's workshop as node A, the art collector's estate as node B, the amphitheater as C, the mausoleum as D, and the hostel as E. I like that there's a mix of places that are entirely part of the order's activities with places incidental to the order and that there's a progression from the mundane to the supernatural. I'm still open to adjusting some of those locations as I proceed, but at least this gives me some prompts for creating clues (perhaps some notable token that can be traced back to the art collector's artisans, a coffin prepared for interment at the order's mausoleum has a name engraved on it, or one of the monks is known as a friend of a stage performer who met them at the amphitheater, just to pull a few examples off the top of my head).
That seems good enough for now. I'll let this simmer in my subconscious for a while before returning to start working on filling out the rest of the nodal map.