Megadungeon Mastery I: There’s No Place Like Home Base

So this is what “urban adventuring” looks like!

I’ve been running adventures in my megadungeon, the Château D’Ambreville, for over two years now. In the process, I’ve made many mistakes and learned a number of lessons about why Gygax and his fellow old-school DMs made the decisions they did in setting up their own megadungeons — Blackmoor, Castle Greyhawk, Undermountain and the like. The following series of blog posts will be an attempt to compile those lessons into a usable format.

(While I wouldn’t say that I’ve achieved mastery of the megadungeon format, “Megadungeon Mastery” has some nifty alliteration going for it, so it’s my title and I’m sticking with it.)

NB: Anyone interested in megadungeon creation should check out this theRPGsite thread on megadungeon design, and this Knights & Knaves Alehouse thread providing an exegesis of an original Castle Greyhawk map.

The location of the megadungeon has a dramatic impact on play. Placing the dungeon in, under or adjacent to a major city doesn’t just allow for easy PC access — which is itself no small thing, as it can save time every session that might otherwise be spent on describing travel or making wilderness encounter checks. It also impacts on magics like floating disk, slow poison or raise dead which have a limited window of utility. (Slow poison is infinitely more useful if you have time to carry the victim upstairs to the surface and just down the street to a temple.) Lastly, it makes random encounters with NPC parties more rational — an important goal if you’re aiming for Gygaxian naturalism — as those NPCs can enter the dungeon as easily as the PCs.

Placing the megadungeon out in the wilderness, as with sites like the Temple of Elemental Evil, changes the equation. Now the party has to travel to get to the dungeon, which can soak up time at the table. (It’s often best to gloss over the trip, especially after the PCs have gone back and forth several times, though that does lose the sense of scale and distance involved.) It also makes tracking the in-game calendar of events more complicated; if, like some old-school games, you have different PC parties wandering the landscape, it’s much more likely that their timelines will get snarled up if each session takes days rather than hours of in-setting time. Meanwhile, NPC parties also have to travel through the outdoors to reach the dungeon, which can result in the PCs spending whole sessions tracking down and ambushing NPC parties in the wilderness — or themselves being ambushed by those selfsame NPCs!

(Either way, the dungeon should have multiple entrances, but that’s a matter for another post.)

Having run a megadungeon outside of civilization, I have to recommend putting one’s first megadungeon in a population center instead. There’s already tons of bookkeeping involved in running old-school D&D, and it’s worth keeping the dungeon right under the PCs’ home base in order to reduce that workload.

As to the home base itself, this can be anything from a peaceful village to a Gold Rush-style shantytown to a major city. The nature and scale of the place has a number of immediate effects. Smaller and poorer settlements may be limited in what wizardry and priestly magics are available to the party, and their merchants are less likely to sell unusual items, may have limited quantities of basic equipment, and may not be able to pay a decent price for some of the valuables pulled up from the dungeon. (This may mean lots of side trips to the nearest city, which you may see as an exciting diversion or an unwelcome distraction.) Meanwhile, larger cities are more likely to host rival adventurers to encounter the PCs in the dungeon or beat them to key treasure hoards.

In the longer term, the political impact of the PCs will also vary depending on the environment. Third or fourth level PCs may quickly become big shots amid an isolated rural landscape, while the same PCs may still be second-stringers in the politics of a metropolis. Again, your choice should be influenced by how closely you want your game to hew to dungeon delving as opposed to urban adventures.

16 Responses to “Megadungeon Mastery I: There’s No Place Like Home Base”

  1. 1 kelvingreen
    May 23, 2012 at 5:27 pm

    It’s often best to gloss over the trip, especially after the PCs have gone back and forth several times, though that does lose the sense of scale and distance involved.

    You can avoid that by having changes happen while they’re away. If things are different to how they were when they left, you still get some of that sense that they’ve been away a while, even if the trip was covered with one “your journey is uneventful” from the GM.

  2. May 23, 2012 at 5:51 pm

    Good point! I tend to do that by incorporating the weather. This can have real impact on play if rainwater drains into the dungeon, or when monsters which go outside leave muddy prints when they return.

  3. 3 Fred Herman
    May 23, 2012 at 6:24 pm

    One thought: Placing the megadungeon right under a population center requires a rationale for (a) how any non-ancient monsters got in there, and (b) why the local populace isn’t being attacked all the time, as opposed to isolated disappearances. (Actually, also (c): What are the humanoids down there eating?)

    As far as (b) is concerned, if the dungeon is a known phenomenon, you might have the city guard constantly posted at the entrances. In which case, they might be actively preventing foolish citizens from going down there, so as to avoid stirring something up or letting something out. You’d end up with something like Roadside Picnic/Stalker, where the adventurers have to sneak their way past hostile guards both coming and going, which might make just getting into and out of the damn place a mini-adventure in itself. This might also give you an excuse to keep your PCs at the “Conan the Thief” social level instead of letting them work their way up to “King Conan” level, if you’re so inclined; their very success at dungeon-raiding makes them professional criminals by definition.

  4. May 23, 2012 at 6:43 pm

    One thought: Placing the megadungeon right under a population center requires a rationale for (a) how any non-ancient monsters got in there, and (b) why the local populace isn’t being attacked all the time, as opposed to isolated disappearances. (Actually, also (c): What are the humanoids down there eating?)

    A) This does place some restrictions on monster choices, but restriction is an important factor for creativity and helps give the dungeon its own unique feel. Do monsters come up from some vast ‘Underdark’ miles below the surface? Are they manufactured by wizards and necromancers? Do they congeal out of the dreams of a mad god imprisoned at the dungeon’s heart? Once you’ve come up with your answer, you’ve got a feel for the essence of your megadungeon.

    B) In addition to your suggestions about the city guard (which are excellent!), monsters could also be restrained by human dungeon inhabitants — the upper levels might be controlled by smugglers or an evil cult, who work to prevent creatures from lower levels from reaching the surface. Other monsters may be too clever to be caught when they come to the surface, or they emerge to hunt in a slum whose inhabitants’ lives are of no import to the city’s masters, or they use dungeon entrances that lead outside the city walls, or they may simply eschew the surface world entirely.

    C) Human inhabitants of the upper levels probably buy food in the city with no one being the wiser. As to other monsters… many won’t need to eat at all (especially if the dungeon is a “mythic underworld”), while others may subsist on rocks or weird fungi or whatever. Most interestingly, the dungeon could easily intersect with the city’s sewers or its rubbish tips, providing a nigh-unlimited supply of food!

  5. 5 Nathaniel
    May 23, 2012 at 8:49 pm

    Based on my experiences as a player and DM I very much agree that a “home base” adds to the fun. Well, really it reduces the un-fun invovled with the logistics of overland travel. So I’m very much looking forward to this thread.

    What I struggle with is a rationale for why a megadungeon exists with anything more than a shantytown nearby. The go-to seems to be mad wizard (Castle Greyhawk, Undermountain).

    Anyone got an awesome idea for a megadungeon near a city that wasn’t built by a mad wizard?

  6. 6 Fred Herman
    May 23, 2012 at 8:58 pm

    It’s the remains of the Old City?

  7. May 23, 2012 at 9:17 pm

    Didn’t Blackmoor have turnstiles leading to the dungeon and holy water fire hoses on hand in case anything got out?

  8. May 23, 2012 at 9:41 pm

    Anyone got an awesome idea for a megadungeon near a city that wasn’t built by a mad wizard?

    My megadungeon is basically an underground Gormenghast built by a sorcerously-inclined noble house. Instead of random labyrinths designed to mess with adventurers, it’s full of nobles’ suites, parlors, dining halls, servants’ quarters and narrow access passages, and all manner of laboratories full of weird magical experiments that love to eat PCs. The place was overrun by enemy troops during a civil war, and the dungeons are still packed with undead dating back to that war, along with a variety of creatures that have either escaped from a lab or intruded from elsewhere.

  9. May 24, 2012 at 5:44 am

    Mine is a series of older parts of the city that connect to the sewers. Some of the older parts are just bits that were built over, while others are underground cities that were built long ago to hide vulnerable people and goods from a long-forgotten invading force. The deepest parts have become connected to otherworldly underworlds, which I won’t explain.

  10. 10 guest
    May 24, 2012 at 8:28 am

    The thing I noticed right away, if you’re keeping strict track of encumbrance in LL and playing solo (1 PC and a DM) and have a dungeon that’s “two days travel” away from town, well that’s two rations for the trip there, two back and one for emergencies… 5 lbs out of 40 if you’re trying to stay light on your feet. It adds up fast. You don’t really have a lot of extra weight to play with. Plus it’s an extra expense you may not be able to afford before you get established.
    It’s just easier attacking some dungeon in town. (Even without the wandering monsters.)

  11. 11 maldoor
    May 24, 2012 at 12:25 pm

    Eric, I am very much looking forward to reading this series.

    About why the dungeon and city are collocated, a historical note: the tell, remains of a city built up over hundreds or thousands of years. Modern-day cities are either on top of or next to many. For a brief description: http://en.wikipedia.org/wiki/Tell

    In the original Empire of the Petal Throne game, Barker went a step further, embellishing the real historical idea of built-up cities and included the Tekumel tradition of Ditlana (p.65):

    “…the ceremonial “renewing” of cities every 500 years: cellars and foundations of an old city are filled in and roofed over, upper floors are razed, and then new and more splendid edifices are built upon this foundation. Such earlier buried habitations are now full of burrows and tunnels built by humans, half-humans, non-humans, and the many parasites and predators of Tekumel who subsist upon man’s leavings. Many earlier temples to the gods of Tekumel – particularly those allied with “evil” – are still maintained in the Underworlds beneath the sprawling modern cities, and it is in these that many of the rich treasures of the ancients are preserved.”

    If you want to put a more AD&D murder-hobo spin on it, simply point out that the dungeon attracted adventurers, who attracted services and camp-followers (gold-rush style). Eventually the successful adventurers build manors and such and a hundred years later you have your city…

  12. May 24, 2012 at 3:09 pm

    @Guest: Good point about travel-based encumbrance and expenses! Also note that old-school DM notes encourage the distribution of treasure in the form of bulky goods such as furniture, bolts of cloth, barrels of wine, etc; forcing the party to haul such goods overland to civilization adds further inconvenience, in which treasure must be brought back on carts and leaving the party vulnerable to bandits.

    @Faoladh & Maldoor: Yes, the built-over ruins of a previous city makes for a classic megadungeon environment. I’ve decided to discuss the matter in my next post instead of jumping directly into the specifics of dungeon design.

  13. May 24, 2012 at 7:19 pm


    That was indeed so. It was the reason I had turnstiles at the entrance of my Dungeon of Voorand. It also has a coin slot beside it which might bestow some luck if you do not cheat. ;)

    As for dungeons under a city, Ed Greenwood’s Undermountain is actually beneath a city, Waterdeep, and the entrance is through a inn. I love that!

  14. June 2, 2012 at 2:03 pm

    For those looking for a mega-dungeon with more than a shanty town nearby I’d suggest looking at the old Runequest supplements Pavis and The Big Rubble. Old Pavis (the big rubble) is essentially an above ground mega-dungeon at a strategic location. New Paivs is small town built by a empire of the current age which is expanding in the area to control the strategic location, control depredations from the Big Rubble, and support expeditions into the Rubble both to recover items and support the second goal of controlling it.

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Past Adventures of the Mule

May 2012

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