Wandering Monsters — Dark Sewers

This week’s Wandering Monsters continues underground. This time, we head into the sewers. Adventures in sewers are rather common and rather than present a whole sewer system, I have instead created just a small section of the waste network. This portion should hopefully be an easy fit to any sewer expedition.

As always, many thanks to the Pyromancers dungeon painter tool for helping me create this week’s map.

Dark Sewers

This smell of filth and waste permeates through these sewers. A section of the wall of the main tunnel has crumbled away, revealing a natural cave beyond.

Click on the maps for full-size versions.

The local sewers hide all manner of secrets and are home to any number of strange residents. All manner of vagrant, ne’er-do-well, and outcast takes residence in the sewer. The PCs may have any number of reasons for entering the sewers. Any PC needing to access the sewer from the surface can find an entrance after 1d4x5 minutes of searching. Otherwise, a successful DC 15 Diplomacy or DC 12 Knowledge (local) will point the PC in the right direction. Finding a sewer entrance in this manner only requires 1d10 minutes of time.

Sewer Features

The sewers are unlit. The walls and floors of the sewers are made of worked stone. The ceilings rise to a height of 10 feet. When the PCs travel through the sewers, there is a chance of becoming lost. A successful DC 20 Survival check is enough to navigate the sewers. Every hour, the PCs must succeed on another Survival check to continue their navigation. PCs that succeed on a DC 15 Knowledge (local) check gains a +2 insight bonus to these Survival checks for the remainder of their time in the sewers.

1. Sewer Tunnels

This intersection is rank with the smell of sewage. The first times a PC enters the area, she runs the risk of becoming nauseated for 1 minute due to the smell.  A successful DC 18 Fortitude save is enough to prevent the nauseated effect. The rushing sewage tends to splash up against the edges of the sewer channels, making the edges of the walkways quite slippery. This is marked by the darker squares on the map. Creatures entering these squares must succeed on a DC 12 Acrobatics check or succeed on a DC 12 Reflex save. Failure results into the creature falling into the water 5 feet below. The rough waters are 10 feet deep.

2. Secret Chamber

A small room is carved into the walls of the sewers in this area. A successful DC 25 Perception check notices the secret door. Inside is usually a hideout of some sort which houses this area’s treasure. An additional hidden room lies within the chamber and a successful DC 32 Perception check detects the extra chamber.

3. Cavernous Entrance

The old stone wall has collapsed leading to a natural cave beyond the sewers. Medium creatures must squeeze through the entrance. A large creature can squeeze through, but doing so require spending two rounds to complete the movement.


The following encounters can take place here.

Encounter Challenge Rating Creatures Treasure
Crazed Scientist CR 7 ChemistVC Scroll of animate dead, scroll of reincarnation, wand of speak with dead (26 charges)
Lizardfolk Outlaws CR 7 3 lizardfolkB1, lizardfolk stalkerMC, 2 lizardfolk vanguardsMC 16 gp, mwk leather armor, longspear

Hidden treasure: 36 pp, 120 gp, 25 sp, 305 cp, bracers of armor +1, gray bag of tricks, rope of climbing

Otyugh Pack CR 7 2 otyughsB1, young otyughB1 Clear spindle ioun stone, pearl of power (2nd level)
This week’s Encounter Table makes use of Bestiary 1, Monster Codex, and Villain Codex.

Crazed Scientist (CR 7)

A local alchemist was run out of the city above for his mad experiments. Rather than fully abandon his work, however, the alchemist instead relocated as much of his resources to a hidden alcove within the sewer. Here, he continues his work, trying his best to animate a construct to seek revenge against the city above. He strikes out to the city to collect livestock and pets to try to fuel his creation, but may soon resort to kidnapping citizens. At any given time, there is a 20% chance that the scientist is out from his makeshift lab.

If the PCs encounter him here, he fights to death to protect his work, believing the PCs are here to bring him in. PCs that manage to capture the madman could potentially turn him in for a reward. While in combat, the scientist attempts to lure the PCs away from his lab and keep the fighting away from what little tools and equipment he has left. If reduced to fewer than 15 hit points, the scientist moves to the secret entrance and drops a bomb at his feet. The bomb will most likely end the madman, but also has a 25% chance of causing the entryway to collapse, cutting off access to the lab. In this case, the PC must spend 6 hours of work to clear the debris.

Lizardfolk Outlaws (CR 7)

A band of lizardfolk broke off from their tribe in hopes of finding success as brigands, assaulting human travelers going in and out of the city. The local law enforcement soon came down on the lizardfolk, driving them into hiding in the sewers. For now, they rest here, planning to return to the surface for a big attack on the city. At all times, one of the lizardfolk vanguards patrols the length of the main sewer tunnel while the other rests in the secret chamber. A lizardfolk guards the cavernous entrance at all times as well. There is a 25% chance that the lizardfolk stalker hides in the collapsed wall. Otherwise, one of the three remaining lizardfolk lies in wait while the rest are in the room. The lizardfolk keep their most important treasure in the smaller secret room.

When the PCs enter the sewers, one of the guarding lizardfolk has a chance of noticing them. If a lizardfolk notices a PC, it raises the alarm. The guards engage the PCs directly. The resting lizardfolk take 1d3 rounds to gather their weapons and join their comrades. When possible, the vanguards try to make a barrier to prevent the PCs from gaining ground. They try their best to push the PCs into the sewer waters. The stalker and remaining lizardfolk do their best to harry the PCs from a distance, spreading out throughout the sewers as the sling attacks from afar.

Otyugh Pack (CR 7)

Two otyugh mates care for their child in this area of the sewer. The otyughs are on edge and one always tends to the child while the other guards the nest. The nest, made of wet garbage, old scraps, and other detritus, is in the secret chamber. The entrance to the chamber is wide open at all times. The young otyugh has an otyugh disease roughly equivalent to a serious cold. A successful DC 15 Heal check is enough to discern this and treating the disease requires a successful DC 22 Heal check.

PCs traveling through the sewers may spot the otyugh parent first. If the PCs attack, the otyugh calls to its partner and the two defend the entrance to the nest to the death. Avoiding an attack instead leads to the otyugh calling out to the party. As the child has been sick for a few days, the otyugh is willing to try anything, asking the PCs if it can help. The otyugh’s desperate please may not come across clearly and requires a successful DC 20 Sense Motive check to properly understand. Failure to help the otyugh causes the monster to lash out in frustration. Helpful PCs are welcomed into the nest. If they can cure the young otyugh, the parents offer their shiniest baubles in gratitude. If the PCs are unable to help the child, the otyughs seemingly bear no ill will, simply shooing the PCs away.

That’s it for this week! Please let me know if you would like see more easy drop-in segments like this one. If you use the dark sewers in your game, let me know!  If you have any request for a future Wandering Monsters, please drop me a line at KnowDirection@hotmail.com.

Luis Loza

Luis Loza is a developer at Paizo, working on the Pathfinder Lost Omens line and formerly on Campaign Setting and Player Companion lines. He's done freelance for Paizo Inc, Legendary Games, Rogue Genius Games, and more third-party publishers. His hobbies include gaming both tabletop and video, making jokes, obsessing over time travel, taking naps with Nova the cat, and walks with heather the wife. He is eternally plagued with a hunger for tacos. Consider checking his material on his Patreon at patreon.com/luisloza