Monday, July 17, 2023

Old-School Essentials: Lairs and Dungeons

 This post is basically me trying to establish the answers to questions the keep coming on and on:

  • What is a lair?
  • What is a dungeon?
  • Are lairs and dungeons the same thing?

I'm going to answer these questions first of all with what's in the Old-School Essentials core book, then trying to make logical conclusions from it. Since OSE is a bx d&d clone, such conclusions should apply to the "whole family" (probably including BECMI and its clones).

What is a lair?

Ok let's begin with good old Merriam-Webster dictionary:


a: the resting or living place of a wild animal.

        "we tracked the bear back to its lair"

b: a refuge or place for hiding.

        "a villain's lair"

Why am I starting with this? Because the rules offer no definition at all, so I believe the only safe path here is to assume "lair" means what "lair" means in ordinary English:

a monster lair is the place where monsters live, rest, and/or hide.

The Game Statistics (Monster) page in the OSE srd, under the Number Appearing (NA) section, gives us the following information:

Number Appearing (NA)

Listed as two values, the second in parentheses.


Monster lair in a dungeon: The second value lists the number of monsters found in a lair in a dungeon.

Wandering monsters in the wilderness: The second value indicates the number of monsters encountered roaming in the wilderness.

Monster lair in the wilderness: The second value multiplied by 5 indicates the number of monsters found in a lair in the wilderness.

Lairs are mentioned again right after that, in the Treasure Type (TT) section:

Treasure Type (TT)

The letter code used to determine the amount and type of treasure possessed by the monster(s) (see Treasure Types). The letters listed are used as follows:

A to O: Indicate a hoard: the sum wealth of a large monster or a community of smaller monsters, usually hidden in the lair. For monsters with a lair encounter size (see #Number Appearing) of greater than 1d4, the amount of treasure in the hoard may be reduced, if the number of monsters is below average.

This is basically all there is to it.

In the rules, a lair is defined by two things: 

  • A variable amount of monsters (a "community");
  •  a (usually specifically) associated treasure type.
Additionally, from the NA section we derive the following knowledge:
  • A lair can be in a dungeon;
  • A lair can be in the wilderness (and has 5x the monsters, but their treasure hoard stays the same!).
Accidentally, I think the first point takes us closer to answering the question "Are lairs and dungeons the same thing?" Spoiler: no.

Let's put it all together and this is the best answer I can offer:

A lair is place where a (typically large) group of monsters (often as an organized "community") live, rest hide, etc, and keep their "community" treasure hoard; monster lairs can be found both inside dungeons and in the wilderness.

Let's work an example?

The Goblin entry in the OSE srd has additional specific information for goblin lairs, so let's see what we get.

  • A goblin lair in a dungeon amounts to 6d10 individuals (and x5 if the lair is in the wilderness).
  • If encountered in their lair, the goblins have a type C treasure.
  • A 3HD (15hp) king and 2d6 2HD (2d6hp) bodyguards live in the goblin lair.
These three pieces of information are the building blocks to create a goblin lair.

An average goblin lair in a dungeon amounts to about 30-36 individuals, plus a 3HD goblin king and 6-8 2HD bodyguards, and a treasure hoard worth around 1000gp.
Yes, that's a lot of enemies for some crappy loot... but type C also has a 10% chance to include 2 magic items!
Considering the swingy nature of random treasure, wise players should try to figure out if a specific lair is worth making an enemy of, before committing to attempted mass goblin murder. Their hoard might as well amount to zero...

Just for fun, let's also consider the largest, richest goblin lair we could finde in the wilderness according to the implied setting: 300 goblins, 1 king with 12 bodyguards, somewhere around 10,000 gp worth of treasure, and 2 magic items.

The only thing that's lacking is: where is this goblin lair? What kind of place is it?

For the most part, we can only answer using common sense and imagination.

The rules tell us it can be in a dungeon or in the wilderness.

In the wilderness, the lair can be anything the specific monster would consider a suitable "home": a cave, a ruin, a hole in a hill, a nest on a mountain peak, the inside of a volcano, etc. And also any type of "home" the specific monster might be able to build, in the case of intelligent creatures: a camp, village, castle, or even a whole city. Remember, NA in the wilderness is x5!

In a dungeon, the lair can be one or more rooms of a larger dungeon. If the dungeon is a small one, the lair can occupy all of it, causing "lair" to be the same as "dungeon". Or does it?

What is a dungeon?

Hey this sounds like the dumbest question. We've been playing dungeons & dragons for decades, we don't need to define what a dungeon is. 

Of course! What I'm doing here is answering the question only with information from the OSE rules, because this will help us understand the difference with lairs.

Again, the rules don't give us a definition of what is a dungeon, but the OSE srd has a whole big Designing a Dungeon page, so my take is: whatever we can infer from that page, gives the "nature" of a dungeon.

The page tells us a dungeon can be a variety of different places (section 1), it has monsters (section 2), you should map it (section 3), and you should stock it with the following "important details" (section 4):

Important details: Monsters (including the possibility of patrols in the area), traps, tricks, treasures, or special magical effects that are present should be noted.

Section 4 continues with the notion that a dungeon often extend over multiple levels, and the deeper you go the higher the risks and the reward, and then notes that treasure is usually guarded by monsters, but can occasionally be found unguarded.

After that, the final section is the Random Room Stocking section. In my mind, this is not just a tool to randomly fill the blanks, but also a set of implicit guidelines. That simple table tells me that a dungeon "as intended" is supposed to roughly have:

33% "empty" rooms (i.e. no monsters and no traps, and about 16% of such empty rooms should contain treasure)
33% rooms with some monsters (and about 50% of such monster rooms should contain treasure)
16% rooms with a trap (and about 33% of such trap rooms should contain treasure)
16% "special" rooms.

These proportions match the intent of "risk goes hand to hand with reward".

In a hypothetical 36 room dungeon, these proportions give us:

10 "empty" rooms (i.e. no monsters, no traps, no treasure)
2 "empty" rooms with unguarded treasure (no monsters and no traps!)
6 rooms with monsters
6 rooms with monsters and treasure
4 rooms with some kind of trap
2 rooms with some kind of trap and some treasure
6 "special" rooms.

This is not all, however, because another important bit about dungeons is found in the Dungeon Encounters page: dungeons are expected to include wandering monsters!

Can we figure out a definition from all of that? Let's try:

A dungeon is a place that: is populated by monsters; features traps (or other environmental hazards); has treasure that make it worth exploring; has bizarre, magical things going on, good and bad (the "special" rooms), and monsters roaming around. 

Are lairs and dungeons the same thing?

Short answer: No, obviously.

Longer answer:

A dungeon can host anywhere from zero to dozens of lairs. If the dungeon hosts 1 lair of monsters, we can say that the dungeon is a lair.
We can look at it the other way around and say that a lair can be a dungeon if it has all the features that a dungeon requires: monsters and treasure, and also empty rooms, traps, and special rooms. In other words: it has to be fully fledged, exciting adventure site!

Let's make some comparative examples with Fire Giants:

  • You can have a Fire Giants lair inside a larger dungeon, with the following numbers: 1d3 individuals, with a type E treasure hoard + 5,000gp.
  • You can have a Fire Giants lair in the wilderness. The description tells us that it should be a black castle near a volcano, with 1d3 x5 individuals, the same type E treasure hoard + 5,000gp, and also the "guardian" creatures listed in the description; 1d3 hydras or 3d6 hellhounds.

The wilderness lair has a lot more giants, but has the same potential treasure as the dungeon lair. How is this fair?

This is supposed to be fair because:

  • The wilderness lair is supposed to be all there is to it, i.e. it is supposed to NOT include traps and wandering monsters.
  • The dungeon lair is supposed to be part of a dungeon with all the "dungeon stuff": traps, special rooms, and wandering monsters. All of that should compensate for the reduced amount of giants.

Can we have another example?

Sure, let's go on with the hypothetical 36 room dungeon:

6 rooms with monsters + 6 rooms with monsters and treasure
It really is up to you to decide how many monster you put into these 12 rooms.
It IS up to you because the BX flavor of d&d does not include a "% in lair" for monster entries, which is featured in the AD&D books and bestiaries.
So you can decide to have zero lairs! Just a bunch of monsters, with some treasure of your choice.
You can decide to have the twelve rooms as a single goblin lair, and this means you'll spread the total number of goblins, and their king and bodyguards, among these 12 rooms, and spread their hoard among 6 rooms.
Or you can decide to have 6 lairs of different creature groups, each controlling 2 rooms. This will give you a much more crowded and dangerous dungeon, but also more potential loot.

4 rooms with some kind of trap
The guidance for traps is sorely short and only amounts to the six examples in the Example Room Traps section.

2 rooms with some kind of trap and some treasure
The guidance for traps is sorely short and only amounts to the six examples in the Example Treasure Traps section.
How much treasure here? The answer is in the Treasure in Empty / Trapped Rooms section, and depends on dungeon level.

11 "empty" rooms.
These have no monsters, no traps, no treasure, so you "stock" them with whatever makes sense for the type of place the dungeon is.

1 "empty" room with treasure.
No monsters and no traps! How much treasure? The answer is in the Treasure in Empty / Trapped Rooms section, and depends on dungeon level.

6 "special" rooms.
The guidance for special rooms amounts to the 9 examples listed in the Example Specials section.

(The truth is, for actual guidance about traps, "empty" and "special" rooms, you should probably check Courtney Campbell's Artifices, Deceptions and Dilemmas).

Does all of this matter?

No, probably! I mean, considering the gm is supposed to roll the dice to determine how much treasure (if any!) can be found in each lair, we can safely say all of this is just guidelines to stock your dungeons.

Not to mention this post is probably the nerdiest thing I've written in my own life. I feel comforted by the fact that if you are reading this, you are at least as much of a nerd as me.

All of this matters a lot if you care for the implied setting and "balance", and if you want to know how much treasure and how many monsters you are supposed to put into your dungeons and wilderness locales.

Even if you don't roll the dice and end up choosing exactly how many goblins and gold pieces you stock your dungeon with, I think it's just nice to know what the expected numbers are, you know, so we try to be all on the same page.
Because those numbers, and the treasure/HD ratio, is the only attempt BX has to make things "fair" and less "whatever the GM thinks".

Especially if you want to write a dungeon module for publishing, I guess.


  1. Hi man. I told you I did my own research about this recently. I came into conclusion that a result of Monster + Treasure in the dungeon generator means there is a lair there, if the chosen monster is able to have one. As sometimes it makes little sense that a whole lair worth of monsters is inside a room waiting for adventurers, it is fair to spread them around the empty rooms or corridors in the dungeon level, having barricades, outposts, rooms dedicated to specific activities, etc.

    But as you conclude, it is up to you to use the In Lair or the No Lair number, as the treasure will be proportional to the danger (though not really: Having to delve through trapped or treasureless monsters has to be done anyways, and once you do that, you prefer to have high chances for treasure even if it means higher enemy number.

  2. Yep. Fun/weird bit is that if you place a Lair into a "Monster + Treasure" room, and you roll the Lair treasure, you might still get no treasure at all!
    It is extra weird if you consider that, for trapped/empty rooms, the treasure table ALWAYS results in some actual treasure being there. Not much, but always some.

  3. Hi Giuseppe, there is a little confusing part. In your hypothetical 36-room dungeon part, you get the result of 11 totally empty dungeons and 1 with treasure. However according to the original table, the proportion is 1-2 in 6 for content and 1 in 6 for treasure, we should get 2 treasure and 10 completely empty rooms. Did you make the result on purpose or with any specific rules?

    1. I... just made a mistake. Thank you for letting me know! Fixing the post right now. THANKS!!


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