D&D Next - 5e Discussion

You'll have to forgive me for my lack of familiarity of the Ptolus setting. I assume a lot of these questions can be answered in the fluff for that world, or explained by DM head canon. The following questions are what I would be asking myself about the space to help guide my design.

• What caused these tunnels to form? Erosion and dissolution, like irl caves, or something more fantastic, like the city formerly (or currently) being part of a Purple Worm's hunting grounds?
• Are there other creatures who live in the tunnels which could prove dangerous? Are they sapient or sentient? Do they hold a grudge against surface dwellers for any reason?
• Does the city attempt to manage these access points in any way? What form does that management take? Is there like a SWAT team of tunnel rats who get deployed whenever something reaches the surface, or are they proactively patrolling the tunnels to prevent incursions? Is there a records office which maintains a list sealed and unsealed entrances? How accurate is that list / how well-funded is that department?
• Does the Thieves Guild rely on greasing palms to keep their operation secret, or do they rely on the inherent danger / inaccessibility of the tunnels to operate?
• Is there a magic user within the Guild who could be responsible for setting up traps, surveillance, or alarms through magical means?
• Have members of the Guild put any effort into expanding / altering the tunnels they use most frequently? Are there capable diggers who would know how to do that well? If not, is there the possibility of a cave-in? Or, perhaps, did they contract out with the Stonecutter's Guild (for example) to ensure the work was done well? Is that an avenue for the players to get some extra information?

As far as general layout of the actual base, rather than the tunnels and subterranean access point, you mention it's in a mid-low income neighborhood, but you don't describe the building they occupy. Is it a house? A commerical venture of some kind? Does the guild attempt to keep up appearances by maintaining a cover of some kind? What sorts of apparatus would they need to keep that cover in place? If the building was originally a bakery, for example, do they continue to operate it as such? Are the employees of the front operation aware of the illicit activities they are covering up? Are they guild members, or are they civilians who are paid well enough not to ask questions?

I regret being all Socratic up in here, trying to answer your question with a series of questions, but I believe they will help you envision the requirements that a base like this would have, which will then guide what elements you need to include to achieve verisimilitude.

Is this a safehouse or a headquarters/guild hall/ hub area for thieves? To me, the former implies a spot for thieves to lay low while the fuzz is on them or to collect themselves and distribute loot after a nervewracking heist, or maybe to stock up on supplies and sleep before moving on to the next safehouse. A place to disappear to, in a sense.

Edit: Or perhaps a place where a thief or group of thieves live and keeps their shit.

Stolen goods that they thought were valuable, but aren’t actually.

Complete with exorbitant prices and backstory. Make it obvious that the seller is delusional and just steals random shit and tries to resell it with a made up backstory.

Make the other theives dislike the seller and if the PCs ask, they say the dude is probably off his rocker. “He ain’t good at theivin’, but he is the nephew of important person” or “he is a really good cook, so we keep him around”

Bonus points if you conceal an actually useful item within the midst of garbage

@juergen_hubert It makes me wonder why there are so many tunnels to begin with. Of course, in a fantasy world they could just be a side effect of unusually large worms, or something.

But first thing that comes to mind is catacombs - if not the primary purpose, a secondary usage. So walls lined with bones is maybe something?

Guard "dogs". Some kind of creature that fulfills the role of guard dogs, maybe trained to recognise a command word to stand down. If the players are able to scout or scry on the place beforehand they might be able to overhear one of the theives using the command. Depending on the setting you can make the creature something more interesting than just a straight combat, like something that tries to paralyze them for interrogation later, something that tries to go and alert the theives, etc.

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).

@juergen_hubert a training area to learn and teach thievery skills

Consider what this place is to the thieves and how they use it.

Do they live here? If so there should be sleeping and dining areas. Do they frequently gather, perhaps to set out for work together, or do they tend to be dispersed, coming and going as jobs demand?

For the former, they most likely a barracks or common room and a dining hall. But if the latter, then something more like a series of tunnels and halls that occasionally have little apartments and safe zones. This is, to use your screenshot, basically the difference between the main guild area and the Ratways.

You say they expect adventurers? Do they set up a few rooms of traps and post a guard to catch them, or do they cleverly hide their entrances and then let monsters roam free outside safe areas as a deterrent, or do they welcome the (money and resources of) the adventurers and so the entrance is guarded but accessible, maybe almost like a lounge or casino?

There's typically a tradeoff between utility and security in any physical space. If it's easy to use the tunnels to get around the city quietly, then it's also easy to lose your enemies, to get lost, and to be suddenly infiltrated. On the other hand, if movement is difficult or dangerous or restricted, then the hideout is more secure from random incursion and discovery.

tools of the trade (say hooks and silent shoes and the like), local pharmacy equivalent (with potions again geared to stealth) and maybe esoteric stolen (demon summoning books) goods they can't sell?

if it's safehouse-safehouse probably appearance altering stuff, food and medicine