I am running an episodic megadungeon using Pathfinder rules, with XP only for found treasure (1 GP = 1XP). Now, I know to restock my dungeon after the PCs traveled an area. I have a restocking system in place, I think it is from Moldvay. Basically, rolling a d20 to see what happens. From 1-13 nothing is restocked in a room. 14-16: monster only. 17-19: monster and treasure. 20: treasure only. My question is:

How often do I roll to restock?

Is there a guideline somewhere for this? Immediately after every foray into an area? Once per session on all explored areas in the dungeon? Or only once per visit of the PCs? Right now I found that my restocking results are pretty oppressive, as in: Lots of new monsters and treasure in cleared areas, which is something I want to avoid.

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    \$\begingroup\$ In my limited megadungeon experience, doesn't the author specify this detail? \$\endgroup\$
    – okeefe
    Commented May 8, 2017 at 19:52

4 Answers 4


The only system I've seen which directly addresses this question is ACKS, which is a B/X neoclone, so it should fall under the "osr" tag. This is covered in the SRD in Chapter 7: Campaigns under the heading "Populating a Dungeon", or on page 141 of the published core rulebook. (While the specific context of that section is determining what monsters move in to a dungeon constructed by a magic-using PC, the author has confirmed on the ACKS forum that it also applies to "wild" dungeons.)

In summary, the method is:

  • Determine whether the dungeon is located in a Civilized, Borderlands, or Wilderness region. In ACKS, anywhere within 50 miles of a city or large town is considered Civilized, the next 25 miles out is Borderlands, and anything beyond 75 miles from the nearest city or large town is Wilderness.

  • Periodically make wilderness random encounter checks for the dungeon itself. These checks should be made once per month in Civilized areas, weekly in Borderlands, and daily in Wilderness.

  • If a wandering monster is encountered (i.e., visits the dungeon), roll against the monster's % in Lair chance. An "in lair" result indicates that it takes up residence in the dungeon.

  • When 1/3 of the rooms in the dungeon are occupied, the dungeon is "full" and any further new arrivals will displace existing occupants (killing, evicting, or enslaving them) and take their place.

  • \$\begingroup\$ That's… a really neat little subsystem. I can imagine the results getting silly in spots ("How did those 3 orcs kick the adult red dragon out of its lair?"), but it make the whole thing sort of occur seminaturally. Thank you for sharing that. \$\endgroup\$ Commented May 8, 2017 at 19:51
  • \$\begingroup\$ @HeyICanChan ACKS is very well-thought-out in general and chock full of interesting subsystems like that. Some of them may be too fiddly for most people to actually use without help from a spreadsheet, but they're great for running a detailed, internally-consistent world. As for the "3 orcs" problem, the average in-lair wilderness orc encounter in ACKS will be with 150 orcs... (But it's a good point - some GM discretion is still required in determining the final result.) \$\endgroup\$ Commented May 9, 2017 at 6:52

This is a decision that rests entirely with you as DM and the answer should be whatever provides the most fun with the least work and cognitive dissonance.

You actually have the answer in your question: "my restocking results are pretty oppressive, as in: Lots of new monsters and treasure in cleared areas, which is something I want to avoid." Therefore the answer is less than you are doing it now. Reduce the amount and if that works, great, if not reduce (or increase) it until you hit the level you are happy with.


The answer depends on the extent to which you restock by using existing dungeon inhabitants (and treasure), and the extent to which the creatures and treasure is new.

As revealed in comments, the restocking introduces a monster roughly 1/3 of the time and treasure roughly 1/5 of the time.

If all of these monsters are new to the dungeon, then this means roughly one new inhabitant per three rooms per restocking.

Consider: How often do new monsters arrive to the dungeon? The usual means for new monsters to arrive are: from outside, from deeper caverns the dungeon is connected to, by spawning within the very dungeon, or summoned by some entities therein. If you restock once every in-game day, for example, and restock 6 rooms on average, you'll get 2 encounters worth of monsters per day. That's probably a lot, unless the dungeon is a part of a large and thriving ecology.

As a contrast, random encounters are restocking can be from existing inhabitants. For example: the carrion crawlers from room 7; the dungeon has a total of 30 orcs; the giant ants grow more numerous at a rate of 1 ant per day (1/6 chance soldier). Or you can look at the fiction and make intuitive decisions: since the orcs were rooted, the kobolds probably expand, so they will trap these two rooms and set a guard post over there.

I'm also running an old school game with Pathfinder rules. One difference from using OSR rules is that combats, and everything else, takes more time. If a single expedition is not over in one session, then restocking between can make returning very difficult, and will create anomalies like new orc tribes often migrating during player expeditions (since there is lots of random encounters happening while the characters are active, and fewer while they are not active).

Since Pathfinder expeditions can take plenty of time when there are several combats, and comparatively little time when there are none, I would recommend restocking once a day, or once a week, or by some other measure related to the fiction. Calibrate the frequency so that you get a plausible number of immigrants to the dungeon due to restocking.


Look at it from the perspective of effects. Do you want the players to have to fight their way in, and then fight their way back out again? If no, then you want it at most once per expedition, after they leave. If yes, then you want it more often than that. Do you want them to have to fight every step of the way, coming and going? then have it restock as soon as they close the door behind them. (Note: this has a decent chance of them eventually deciding to just loot the same room over and over again). If you want it somewhere in between, I'd suggest that it should restock when they leave a general region of the dungeon. That way, they still have to worry about fighting their way back out again once they're done, but they can run around between cleared rooms in the local region figuring out puzzles and the like without constantly being assaulted.

Alternately, maybe full-on restock isn't really what you want. If what you want is for them to have heavy battles on the way in, but only occasionally fights on the way out, then you effectively want a wandering monster table (even if it's represented by the rooms being occupied once more). Don't make restock rolls on every room after they've left the region - just one or two. Maybe add another restock roll to each cleared region for every night they camp inside the dungeon as well. If it doesn't split up evenly into regions for you, then perhaps roll for a single room each session (assuming they're clearing more than one room per session).


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