The PCs are likely are going to try to get into a safehouse of the local thieves' guild in the next two sessions. The setting is Ptolus, using the D&D 5E rules.
The safehouse in question is in a lower middle class region on the surface, but it has another entrance to the vast dungeon systems beneath the city. This, in itself, is not unusual - the bedrock on which the city stands is filled with tunnels and long-forgotten vaults. But while most house owners just try to brick those passages over, the thieves' guild actually uses these passages for their business dealings.
And I need some ideas on both what might be inside the premises, and what kinds of systems they use to secure the safehouse. The PCs will likely be coming from the "dungeon" side, and this is the kind of city where criminals expect inconvenient adventurers to pop up in all sorts of places.
I've already determined that the location includes:
- a vampire ally of the guild
- some cells for prisoners who get interrogated for information
- a bunch of drugs for resale
Any other ideas? The party consists of four 8th level characters, if this helps.
For some laughs you could probably mix in some bad ideas with good ideas; for example the guild uses mimics knowing adventurers are greedy for more gold and go to the trouble of making it look like they were supposed to be hidden, like for example behind hidden walls (that they know adventurers like to poke around in); however they also try to keep some important doors closed by just sticking a chair under the handle (good ideas + bad ideas).
You could have that they set up a boulder trap, except their architectural design was off and the boulder after a short period inevitably just veers off of a nearby chasm rather than down a suspended path as they'd originally intended.
You could have them make piles of 'gold' that have explosive rune cast on them, and if they should meet the adventurers in battle they can literally call out the rune and the coins explode, except they used pyrite (fool's gold) because they were cheap, and perceptive adventurers will notice the 'gold' is worthless (and may even get them in trouble if they try to spend it).