Designing a Thieves' Guild 'dungeon'

I’ve been working on a series of adventures in a big city called Vermilion with my Patreon. It was supposed to be one mini-adventure, but I learned that city dungeons can quickly become similar to mega-dungeons. Tons of different buildings, a variety of NPC’s, several factions….all kinds of things that can be happening in the background that the party can choose to get into some trouble or ignore. At some point, I may write about designing city adventures because I think it’s a good topic and feel there is a dearth of city adventures out there, but instead wanted to focus on a thieves’ guild 'dungeon'.

One thieves’ guild in Vermilion is called The Shiver. I give a few situations or adventure hooks of why a party might find themselves prowling around within their halls, whether they bite or not is up to them. But I felt there were enough reasons why they may enter, so I decided to map and key it out.

I poked around the internet for ‘Thieves’ Guild as a dungeon’ and didn’t pick up much—some was about forming a thieves’ guild, etc.. But I did find a little and seems most believe that traps and secret doors are the meat and potatoes for the inside of a Thieves’ lair. I don’t necessarily disagree with that assessment, especially the secret doors part, but I also felt the thieves’ don’t want to be hampered by traps all the time (especially the new members!) and if it was easy to bypass, the trap may start to look more evident or how to bypass it.

Then I thought about The Shiver. Vermilion is located on an island, so a successful guild may need to keep its cool on robbing everyone as eventually it might catch up to them. So most of the thieves target pirates or foreigners for pickpocketing with maybe a rare mansion robbery in the rich district. So then I figured if the thieves were hesitant to approach the rich, perhaps they would have the rich approach them….so suddenly my thieves’ lair exploded to have a underground amphitheater and fighting cages. They would organize gambling events…Fight Nights. They would rig it so they took an unnoticeable amount of coin from the top, and have a door entry fee. The rich felt safe attending these Fight Nights because I made it into a masked event. So no one had to feel guilty as no one knew who was who. Plus, it made it a little easier for a party to enter (if they have masks).

This set-up got me thinking that everyone would believe that this fighting arena, under a warehouse, was basically all that was down there. So the thieves’ lair was essentially hiding in ‘plain view’. A few secret doors….a few traps, and most of the other areas are hidden or safe from drunk attendee’s. By having this fighting arena, it just blew up some options, as I’m finding that city adventures often do….so now the party could be down here to watch Fight Night, or maybe they want to fight in it, or forced to fight in it, or maybe they are here to do a job (i.e. kill the guildmaster as the original adventure hook), or maybe they want join the guild, or maybe they want to rob the place…

So I decided to continue with the map and it became two levels. I wanted tunnels leading off every which way (to the market, to the sewers, to the city council, to the harlot house, etc.). I wanted a few bunk rooms for thieves who needed a little hideout for things to slow/cool down on the streets. So this brought the usual—kitchen, pantry, a small shrine to a thief deity type, costume room, and planning rooms with small clay terrain pieces to case jobs, etc. But I wanted to make it more interesting than that….

I started to add training rooms. A room for practice skills in open locks, hide in shadows and moving silently. The first two were semi-easy, with chests and different locks, and an irregular room with some light sources. The move silently room suddenly became an area with some blind monsters in it…the whole place reeking of garlic to ‘blind’ the other senses to these creatures. Thieves would be tested to bypass them by moving silently to claim the prize on the opposite side, however the party may not catch on to that and have a fight on their hands.

Finally, I have a process that when chests of gold =1,500 gp from collections at the door, as well as collections from the fight...its wheeled off in carts and valuable loot spilled down a funnel pit, into the unknown. This could serve as an adventure hook on its own as the party may want to discover where exactly that room is to get to the loot. And how would a thieves’ guild protect this money from all the….thieves? Is there honor among thieves? Probably not....

Hence a short labyrinth full of traps to get to the vault. None of the guild members wanted to test their luck, although there was a scroll marking names of those who tried. Lot’s of different traps, and I tried my hand at riddles once more (I suck at riddles!). Finally…a new monster to guard the room itself.

Overall, I finished with a 2-level thieves’ guild ‘dungeon’ that has fighting, roleplaying opportunities, traps, puzzles, and several reasons for why a party might find themselves down there. Probably a good night's worth or more of play time material. Now to finish the wilderness section and three other mini-dungeon areas I want to get done for Part 2 for my Patreon members this month!