This is my fourth post in my new series: an open-table West Marches campaign for Old-School Essentials. So far, I have sketched out the home base and the surrounding area. Today, I want to get started with mapping the first few passages of the Drowned Labyrinth, the primary megadungeon.
For playability reasons, I should probably start with the safest entry point: probably most parties’ first experience of the dungeon. But that will come later. Instead, I want to design a part of the dungeon which best captures the spirit of the rest of the dungeon. A taster, if you will, much as the first level of Undermountain feels archetypal of the whole.
As explained in my first post on the Labyrinth, my main influence is ‘the House’ in Susanna Clarke’s Piranesi: a world of seemingly infinite chambers and corridors, flooded middle levels, misty upper halls, and depths drowned by the sea itself. Some spaces are light and beautiful; others are old, damp, dilapidated. Architecturally it is classical, with columns, high ceilings, white marble, alcoves, statues. It should feel like a museum without end: eerie, vast, and faintly alive.
Will all of the dungeon be like this? No. But it still seems like a fun place to start!
Just as some songwriters start with a tune and others start with the lyrics, some adventure-writers start with a map and others don’t. Personally, I’ve always found mapping intimidating: not because I can’t draw (I can, well enough) but because I struggle to visualize spaces in my head and tend to find a blank page overwhelming. So, before I map, I make lists: inhabitants, hazards, treasures, special features. And once I have lists, I sketch out areas in abstract, and only later does an outline become a map.
Let’s start with inhabitants. I want at least one faction if not two, and factions are generally intelligent, humanoid, or both. In my last post, I mentioned the Cult of the Prisoner and the Drowned Ones. These seem good. I’ll either need to come up with a stat block for your typical cultist or use the deep one stat block, and the Drowned Ones will probably be aquatic variations on ghouls and zombies.
As for other inhabitants, I like the idea of a Greco-Roman theme. A minotaur would be fun, or maybe a predatory medusa, like Harryhausen’s. Where there is water there are oozes, eels, maybe giant rats, although I don’t want it to feel too much like a sewer. Lacedons (watery ghouls)? Maybe a ghost or a banshee (both of which are No Joke in Old-School Essentials). Giant crabs. Gargoyles? Maybe—but caryatid columns (a new monster to me) seem more apt. Old-School Essentials doesn’t have stat blocks for chuuls, gricks, or water weirds, but I can probably homebrew them.
Other hazards? Well, we already have water; I picture this being about a foot deep across most of the level—shallow enough that characters shouldn’t have be slowed down, but with deeper sections where wading or swimming is required. It might be fun to have false shallows that the players can take advantage of (or get caught in), entangling kelp, sliding doors that seal off exits, and maybe some poison darts. A singing statue might be interesting, acting a bit like a siren’s song perhaps. As a puzzle element, I wonder about including some kind of ancient machine (or multiple machines) that can be used to raise or lower the water level: the sort of thing you might find in a level of Tomb Raider.
What about treasure? Three-quarters of XP comes from gold in OSE, and besides, treasure can be a great form of storytelling. I’m imagining amphorae of coins, bronze statuettes turned green over time, torcs, golden circlets, coral necklaces or rosaries, a beautiful conch, and, of course, whatever they find on the corpses of rival adventurers. Jewellery and gemstones might be found offering bowls, tiny coffers, statue eyes, or half-buried in silt. In Ancient Greece, the dead were buried with coins over their eyes (obols); perhaps these can be pried from the Drowned Ones once they’ve been defeated. Marble statues would obviously be worth something, as might mosaics and frescoes, if the party can devise a way to take them with them. And while it might be more of a ‘discovery’ than a treasure per se, a raft would be a fun, and useful, find.
There’s plenty to be working with here. Something else I like to think about is what you might call the ‘rhythm’ of the dungeon: the rough balance of traps to monsters to empty rooms. It’s why some dungeons feel like a gauntlet and others feel a haunted ruin: why some feel like a treasure vault and others feel like a deathtrap. The standard advice in OSE is to have about one-in-three as empty rooms, one-in-six as traps, and one-in-three with monsters, and as a general principle, the greater the danger, the greater the reward. For this part of the Labyrinth, I’m going to go with the following ratio: 20% monsters, 15% traps, 45% empty, and 20% special (eg, puzzles). In play, this should mean long stretches of quiet exploration punctuated by occasional danger and moments of strangeness, with tension coming from uncertainty and attrition rather than constant combat.
Another ‘dial’ to play with in this regard is the chance of wandering monsters. I think many of the monsters mentioned earlier would make more sense as roaming threats than as keyed encounters. TV Tropes has a page called ‘Orcus on his throne’—I don’t want that. Wandering monsters are also a key dungeon-crawling procedure in OSE and other B/X retroclones; an one-in-six chance of a wandering monster every two turns (the standard) will feel very different to, say, a two-in-six chance. I’m going to go with a 1-in-6 chance every 3 turns to make the Labyrinth feel desolate and vast, not too busy or highly trafficked.
Let’s put this all together. Assuming we have, say, five or six traps, about a few more keyed monster encounters, and a decent amount of treasure, we probably want at least 15 empty rooms in this complex, or thereabouts. In total, I think we’re looking at a dungeon of at least 30 rooms and probably more, plus doors, corridors, entry points, and so on. (And of course, few dungeon rooms should be truly empty. A chamber without traps, monsters, or treasure can still be flavourful ambient storytelling, or indeed, a site for a random encounter!)
All the remains now is the map, and deciding exactly how to stock and key it. That’s my job for the next article, which I hope to share on Patreon in the coming weeks. Or would you like to see more of the Drowned Lands, or another dungeon level? Let me know in the comments below.
To subscribe, click here. If you like what I do, please support me on Patreon or buy my products on DriveThru RPG. You can follow me on Bluesky @scrollforinit and Instagram @scrollforinitiative. And if you want to make my day, you can buy me a coffee here.