I have far too many RPG-related PDFs, and sometimes, I just start reading one to see what's in it. Today's reading was this:
So I am reading about establishing dominions in ye olde Companion rules (book 1) and find this bit about magic-users (what earlier editions called wizards) on page 19.
After the magic-user moves into the tower, a dungeon may be built beneath or near it. The dungeon is most often constructed by hiring specialists in mining, but can be created magically if the proper spells are known and used. When one or more levels of the dungeon are completed and thereafter left open, monsters will start to arrive and build lairs. Shortly thereafter, low-level adventurers may start arriving to seek their fortunes.
First a magic-user builds (or captures) a tower, then they build a dungeon. Creating dungeons is the expectation of land-owning wizards. The quote speaks of specialists in mining, but if digging dungeons is as commonplace as the above quote suggests, there are likely specialists in dungeon design, architecture, engineering, and building.
It's likely these specialists are often Dwarves, which in turn helps explain why Dwarves are often so wealthy - wizards pay well for their skills, and the Dwarves deliver. It is also implied that magic-users choose sites for towers based partially on the ease of building a dungeon - which means specialist surveyors, who again, are likely Dwarves.
If there are specialists in siting and building dungeons, there must be specialists in attracting the right kinds of monsters to lair therein. Even if many monsters are migratory, various critters have expectations of living. For example, if a magic-user is hoping for giants, the dungeon halls had best be 20' high and probably as wide. Maslow teaches us that all creatures need food and shelter, so ready food sources had best be found within or near the dungeon, as well.
Food sources like rat-on-a-stick franchises, maybe.
The quote also states that dungeons can be created magically if the proper spells are known and used. I'd think Wall of Stone, Stone Shape, Disintegrate, Dig, and summoned Earth Elementals would be baseline requirements, but no doubt others would help, as well.
All of this sounds like a hassle and makes me wonder why the magic-user wants such dangerous neighbors (tenants?) so close to home.
The book tells us why, providing this motivation for magic-users to build dungeons:
Most magic-users with dungeons visit them once each month (or more), gathering any magical treasures that remain. If too much treasure is taken from the monsters, they will probably move out. Occasionally, if done quietly and secretly, the magic-user may capture some of the monsters for use in magical research and potion making. This must be done carefully, lest the remaining monsters be scared away.
It appears that magic-users create dungeons expressly to farm magical items and to have a ready source of experiment-fodder and potion components. This implies dungeon-digging landed magic-users have a side-hustle brewing potions, making different formulae trade secrets that are no doubt worth killing and dying for.
All this makes landed magic-users almost ideal patrons, both to the low-level adventurers who plumb their depths, and also mid-level adventurers to help stock their dungeons. These adventurers may also be the same ones bringing new magic items into the dungeons, as well as a regular customer of the magic-user's potions.
This also suggests that Dwarves may well have a monopoly on dungeons dug by hand, with various clans specializing in different aspects of dungeons. It also means that veteran adventurers can take advantage of knowing how different clans build things: "this looks like Stonehammer work - which means we need to watch for sliding walls and floor chute traps."
A world built around new dungeons appearing on a semiregular basis allows for an ideal game world - at least for me and my sporadic gaming.
In light of this, I have some campaign world revising to do.