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.
- 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!).
- 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.
What is a dungeon?
Important details: Monsters (including the possibility of patrols in the area), traps, tricks, treasures, or special magical effects that are present should be noted.
Are lairs and dungeons the same thing?
- 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 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.