Could use some ideas for a sewer crawl.


Advice


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4th level party will be going into the absurdly spacious sewers soon, trying to reach the abandoned underground city buried beneath the regular city.

I'm a bit lacking for sewer ideas, though. I can think of otyughs, and... well, that's it. I know they're escorting a bumbling weaker-than-them warrior with a penchant for charging into trouble and needing to be rescued, but I can't really think of anything to do here. Help?

Silver Crusade

Pathfinder Adventure Path Subscriber

Kobolds could be a good monster, wererats, I imagine some arcane energy runoff could create a sewer Water Elemental.


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The scariest thing to see in the sewer is a human, because you've got to be a pretty desperate human being to wind up down there.

Givem some rat companions for flanking and flavor, plus the filthy weapons feat. Go skirmishy or go home. Attrition and ambush all the way.

Silver Crusade

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Pathfinder Adventure Path Subscriber

A ratfolk monk and four nagaji fighters wearing medium or heavy armor made of turtle shells?


It's a classic way for the "bad guys" to travel secretly back and forth between above ground locations. Smugglers, Robbers (think of all the 'rob the bank' movies you've seen where they're tunneling in), Kidnappers, Escapees from the Jail (or slave pens or ...).

Escaped pets ... from the normal lost dog to snakes and alligators or worse.

What's in the abandoned city?


Aside from the excellent suggestion above, slime, mold & Gelatineous Cube are also a good addition.

For something different, sewer troll (Monster Codex) would he great.

What else: Ettercap and spider, centipede, cave fisher, rot gub, leech, zombie, skeleton, ghoul, ghast, doppelganger and skum.


Kayerloth wrote:

It's a classic way for the "bad guys" to travel secretly back and forth between above ground locations. Smugglers, Robbers (think of all the 'rob the bank' movies you've seen where they're tunneling in), Kidnappers, Escapees from the Jail (or slave pens or ...).

Escaped pets ... from the normal lost dog to snakes and alligators or worse.

What's in the abandoned city?

The old queen's a mythic NPC with that ability that lets her grant spells like a deity (the party's Warpriest has her as a patron). Back when the place was still in use, the queen had herself bound and restrained down there to protect her subjects from her lusts and rampages. She's still all tied up in the old city's palace, and the PCs need to get some information from her that's more specific than can be conveyed by any of the divinations they have access to. So they need to go ask her in person.


Well any sewer adventure isnt complete without an Otyugh. Theyre filth eaters and right around your parties level.

I also like to do Oozes in such settings because sewers are perfect for them. They just sit there and all the waste and refuse they can eat literally comes to them. A gray ooze is right around CR 4 but if you wanted to make an ooze encounter much harder you could use a black pudding

You could also do a mercenary group that died down there making a section of the sewers haunted by a band of skeletons lead by a skeleton champion. You might have to add class levels to give 4th level characters a better challenge though

One idea that just jumped into my mind was a mad sorcerer who happens to live in the sewers and he may or may not be willing to do some trading with the PCs (maybe he brews potions?) but they should be wary of the Junk golem (CR4 bestiary 4) guarding his home

Personally I also love the idea of the old "crocodile in the sewers" urban legend and like to put something like that in. While a crocodile is CR 2 you could easily increase that with the advanced and Giant templates. Alternatively you could also play it as a case of mistaken identity and put a crocodile looking lizardfolk in who may or may not be friendly depending on the PCs actions. Just give it as many class levels as you feel would give an appropriate challenge


Disease. If the players are walking in filthy water during or after combat they'll have wounds. Get some of that wholesome bacteria laden water in a wound and you have the chance for Filth Fever right off the bat.

Grand Lodge

Derro, undead, collapsing sewer walls, swarms of rats or beetles, crazies who believe they're the rightful heir to a kingdom that never exists, a mechanical switch that knows when you're gonna try to flip the switch to open the door of a flooding chamber...


Quote:
The old queen's a mythic NPC with that ability that lets her grant spells like a deity (the party's Warpriest has her as a patron). Back when the place was still in use, the queen had herself bound and restrained down there to protect her subjects from her lusts and rampages. She's still all tied up in the old city's palace, and the PCs need to get some information from her that's more specific than can be conveyed by any of the divinations they have access to. So they need to go ask her in person.

:D Well obviously the legends of the Queen have inspired a crazed group of fanatics (heretics to the Warpriest) determined to free her ... so there must be cultists wandering around searching for the way down into the Old City along with hidden cultist shrines within the sewers.


Kayerloth wrote:
:D Well obviously the legends of the Queen have inspired a crazed group of fanatics (heretics to the Warpriest) determined to free her ... so there must be cultists wandering around searching for the way down into the Old City along with hidden cultist shrines within the sewers.

I like it, but I think I'll save that for later. A "Defend the dungeon" plot could really shake up the formula, and it'd make more sense to put that in the palace. No reason I can't have a cultists scouting party or something for some foreshadowing, though.

Dark Archive

Andre Roy wrote:

Aside from the excellent suggestion above, slime, mold & Gelatineous Cube are also a good addition.

For something different, sewer troll (Monster Codex) would he great.

What else: Ettercap and spider, centipede, cave fisher, rot gub, leech, zombie, skeleton, ghoul, ghast, doppelganger and skum.

I thought spiders didn't like wet places. I could be wrong though.

Excrementals? Just take a mud elemental and give them the Stench ability from a troglodyte. Or you could just use an ooze, but elementals come in all shapes and sizes. 2 medium mud elementals or 1 large one would work.
A lacedon that hides underwater to ambush unsuspecting creatures by grabbing them, pulling them underwater and drowning them. you might want to give it the advanced template.


Goblins are traditional. Little buggers live anywhere people don't frequent.

A suspiciously section of the sewers walled off with wooden planks and No Tresspassing signs could contain a local necromancer's stockpile of zombies. No clue left behind to lead you to the necromancer, but you know he can't be too far away.

A solitary hag living in the sewers, dreaming of forming a coven steps away from the prey she hunts.

This might be the only opportunity you have to face the party against...a fish. this catfish is kind of nasty. Especially since the murky water would hide its movements.


the David wrote:
I thought spiders didn't like wet places. I could be wrong though.

Maybe, I was spitballing so, granted, some of my suggestion might be off.

But if the PC vers into a dry tunnel or a dried-up cistern (or in the upper part of a water-filled one)...it could work


These. So much these. Came close to wiping out a 5 member party of 5th level players while they waded across a marsh with them.

Belostomatid


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Giant centipedes, and with them creatures with Vermin Empathy (I prefer mites myself). Swarms, intelligent creatures using their poison, and Medium or Large sized ones bearing riders.

I have used Reefclaws in a coastal city's sewers too. Anything that grapples a PC and drags them into the water. You could also go with boggards for this.

A Small sized black dragon might be interesting. If it were being protected/fed/worshipped by kobolds who in turn laid traps all around, that could be a whole sub-level of a dungeon unto itself.

Undead are of course fun and have been mentioned, but what about animated objects? You could advance some homunculi, give them a means of animating stuff, then make monsters out of the bigger flotsam and junk in the water.

If the sewers are "absurdly spacious" and a transition point to an older settlement below, adding some secret chambers from the ruins could be fun. You could drop in a lamia variant cleaving to the faded memory of old, perhaps dominating flora or fauna nearby (such as oozes/fungi, dire rats or dire bats, etc) but these chambers are crumbling; add some CR 1 crumbling masonry traps or something.

Blight druids, or the one archetype built around surviving in filth might make an interesting foe. There are a couple druid archetypes that synergize with swarms so that's something to keep in mind.

Outside of the usual diseases that sewage can carry, what about outright drowning? Setting up a chase mechanic with a flood of rushing water or perhaps having a tunnel collapse into a full cistern can add a skill challenge. In fact, if you use the chase mechanic you could insert a variety of skill challenges to really get your players thinking outside the box.

Arcane magic is not often associated with sewers, but malfunctioning spells in place to manage the sewers might make cool traps. Hydraulic Push for example might be a supernatural water surge meant to keep an intersection clear of obstruction but instead a pipe is broken and the water jet now sends PCs flying into a wall or something if they're not careful.

Finally, I really enjoy alchemy in sewers. Runoff from labs or workshops in the city mingles with the other muck below. Alchemical ooze swarms, alchemy golems, maybe even any intelligent creature capable of crafting with such volatile substances to harness their power? For this, what about evil grippli? Give them the Toxic Skin trait, plenty of alchemical weapons, levels in Expert and Warrior with a leader with levels in Alchemist, and some oozes and swarms at their command!

The sewer environment is itself an enemy. Acrobatics checks, Swim and Climb, plus the usual dungeon crawl abilities are useful. Also because of the lack of sun it can get damp and cold leading to mundane fatigue. You also have diseases, slime hazards, miasma and gasses... all of these provide ample distractions for the worthy adventurer!


Of all the scary things that lurk in the sewer, nothing is scarier then the possibility of drowning in muck.

Perhaps give subtle clues that it has been raining pretty heavily before they even go down inside. All the sudden flash flooding, leads to full flushed sewer pipes.

Even if it's only a few moments of having to hold their breath, you could force the party to have to act in panic mode without actually being in combat. You could apply several conditions too (darkness, squeezing, sickened, etc.) that make simple actions much more difficult.

Imagine filthy water rushing through the pipes, submerging the party. The water and the flotsam within makes it really difficult to swim towards the diverging pipes, and it could be so filthy as to the sickened condition.

Maybe the wizard casts light to try and see through the murky water, the fighter has to try to bash a grate open for them to escape, all while trying to hold their breath.

Even if the deluge of water only lasts for a couple rounds before alleviating, it could really scare the pants off the group with the illusion of a non-combat TPK.


"The Styes" from Dungeon #121 is designed for 9th level. It is sequeled in in #138's "The Weavers." It is the perfect sewer crawl.


You have them in a sewer! Turn their lights out and then hit them with something that can see in the dark just fine.

How to turn their lights out? Man, how do I count the ways. Guy holding the torch hits a slippery patch -- Reflex save or fall, torch/lantern goes in the water. Ssst. Goblin ambush targets the light source first. Fzzt. Spellcaster with Darkness, Quench, or Pyrotechnics. Blip. Party hits a patch of flammable gas (which is a no-kidding real threat in real world sewers). Boom!

"But the sorceror can cast Dancing Lights..." Not if he's grappled, he can't. Or if one goblin has held an action to shoot him as soon as he starts casting. Or if he's just fallen into a 10' pit full of foul water and is trying to make a Swim check. Or if the creature that was stalking them, and that has just charged as soon as the lights went out, is now threatening him.

Oh! Swim checks! I notice that one, two... three of your four PCs are heavily armored! And, hey, paladins and clerics don't usually invest ranks in Swim, do they. You know what happens when you fail a Swim check? "Fail by 4 or less, you make no progress." (i.e., you stay splashing in the same spot.) "Fail by 5 or more, you go underwater." So: slippery slopes, requiring Reflex saves, above water. Sewers have algae and all sorts of slimy glop. You just say "this area is really slippery. If you want to move more than 5 feet per round, you must make a DC 15 Acrobatics check -- fail and you fall prone... and slide into the water" Then, in the water, something nasty.

Seriously, sewers are great.

Doug M.


Here's one I used on my own PCs a while back. PCs come to an area where the stench of rotting flesh is overwhelming. They think "undead!", slow down, and go on the defensive.

In fact they're passing underneath the local slaughterhouse. After a few rounds, there's the sound of a hatch opening... and a couple of hundred pounds of offal come sliding down a chute. It's a DC 12 Fort save or be nauseated for 1d4 rounds. Meanwhile, the vigorous sewer ecosystem responds immediately: two advanced rat swarms and a carrion crawler.

The carrion crawler sadly did not make it into Pathfinder, but there are half a dozen monsters that will fit as well. Note that swarms are incredibly obnoxious opponents if you don't have the right spells ready.

Doug M.


Oh! Almost forgot: it looks like your group is mostly human, amirite? No gnomes or halflings?

So: who says that sewer tunnels have to be the standard dungeon 10' x 10'? Put in some sewer tunnels that are 5' tall and 3' wide. Squeezing through a space too small for you = -4 to hit and -4 on AC. (Yep, there's a rule for it.)

Let's add up the possible things you can throw at them now:

Slippery bits
Climbing
Swimming
Water hazards (powerful currents, creatures in water)
Lighting issues (low light conditions, full darkness)
Nauseating smells
anything that needs a Reflex save
Swarms
Cramped tunnels
Difficult terrain
Gases (unbreathable, poisonous, explosive)
Ambushes
Traps (deadfall, tripwire, pit)
Locks
Diseases (on creatures, in water)

-- and this is mostly environmental stuff; we've hardly cracked open the bestiaries yet.

Let's mix-and-match for a sample encounter. The passageway opens up into large chamber, with a 1' wide ledge around a pit. The pit is 15' across and partly filled with water. The surface of the water is 10' below the ledge. There are several drains in the walls of the chamber; water is pouring out of them down into the pit. The air is warm, foul, and filled with a thick mist -- treat as an Obscuring Mist spell, giving a 50% miss chance beyond 5 feet. (Note that this means the PCs cannot see the surface of the water below them.)

The ledge is wet and slippery. Moving more than 5' per round requires a DC 15 Acrobatics check; failing this will send the PC over the edge. A DC 16 Reflex save will allow him to grab the edge of the ledge, but otherwise he falls into the water. The ledge is considered a cramped space, granting a -2 to attack rolls and on AC.

An otyugh lives in the water. It's a mutant with webbed feet, Swim speed 20', and blindsight instead of darkvision. The otyugh is hungry and will attack anyone who moves onto the ledge. It has a 15' reach and will try to grab a victim and pull it into the water. (The grab ability means it gets an automatic grapple attempt at +13 whenever it hits with a tentacle. Note that it will probably get a surprise round unless the PCs are specifically watching the water.) Once the otyugh gets someone in the water, it swims downward (the water is 30' deep) and tries to keep the victim underwater until it drowns. Attacking the otyugh is not easy; the mists give it concealment even when it's at the surface, and once it's underwater it can't easily be attacked without jumping into the water.

The otyugh isn't alone. Two rat swarms lair behind the walls. The otyugh occasionally tosses them scraps -- it considers the rats its pets. The rats will swarm out of cracks in the walls one round after the otyugh starts attacking.

If the PCs get past the pit, they will find that the passageway out of the chamber is blocked by a locked gate. Four goblins wait down the passage -- they're aware of the otyugh and have a truce with it. They'll launch javelins at any PCs who appear at the gate. If a PC starts picking the lock or bashing down the gate, they'll switch tactics and throw alchemists fire, making it impossible to bash the gate without taking fire damage (unless the PC has a reach weapon) until the fire burns out. Their goal is to keep the PCs in the room with the otyugh and the rat swarms for as long as possible. If the PCs break through the gate, the goblins will flee.

Is this the sort of thing you're looking for?

Doug M.


I was looking at Otyugh the other day and considered a sewer-crawl where they were friendlies instead of enemies (since they're Neutral and speak Common). I envisioned one collecting discarded furniture and wire-spools, making a sewer bachelor-pad, and being hospitable towards the PCs.

Here are a few other encounter ideas:

Giant Amoeba and Amoeba Swarm. They have blindsight, so they can be a formidable hazard in places with limited or no visibility.

Sewer Gas. Poor ventilation can trap methane. Unprepared explorers using fire to light their ways can cause a nasty explosion.

Rat King. Someone who feeds rats. The rats have become friendly to him and will not attack him. He has no special control over them, although has come to think that he has.

Cockroach. Cockroaches are plentiful in places where there is moisture and food. The Giant Cockroach varieties and the Cockroach Swarm can make for stronger monsters, if needed.

Outsider(Water). Tritons or other outsiders/elementals trying to purify some of the larger pools to make them habitable. Because why not? You could also have some darker encounters where there are some Degenerate-templated outsiders who were driven mad by the pollution while attempting to cleanse it.

edit: This would also be a great place for Vegepygmies or Myceloids as friends or foes.


As a capstone encounter (APL +5) perhaps the nuckelavee. This thing is pretty powerful but you could foreshadow it a lot through the crawl. Perhaps there's an "avenging spirit" in the sewers known to the otyughs that rises out of the water to spread a plague of retribution.

Also at Dougy Fresh: whoa! So you've got environmental hazards favorable to the otyugh; a mutant aberrant creature ideally suited to said environment; 2 rat swarms on a 1 round delay. The otyugh alone would be a CR 4 encounter. The water, if it becomes a hazard, is a 30' pit so roughly a CR 1; persistent Obscuring Mist/CR 1; each rat swarm is a CR 2; the 4 goblins are between a CR 1 and CR 2; the locked grate likely adds 1 to the overall CR as does the narrow, slippery ledge... I'm figuring a grand total of 3,740 XP in the threats/hazards of the encounter, between a CR 7 and 8, +1 from the ledge and grate, so about a CR 8 - 9 in the end.

I am however stealing the "offal dump" encounter for my own game. I'm always looking for ways to justify ambient Condition-inflicting threats like this. Walking near lava and having the heat and fumes inflict Fatigued; at low level trying Dazzled on anyone entering a room with sparkling crystals with a strong light source; necromantic cysts in a crypt pumping out nightmare auras that deliver Shaken or Frightened on anyone in the vicinity. These combined with the right monsters is a really fun, tough encounter which, used sparingly, really seems to hype my players.


An old time favorite: degenerate halfling cannibals with filed teeth. Warrior/rogues who tumble into Sneak attack positions.

Good old TPKs.


* This is a good time for a Gelatinous Cube. Stick it around a corner in the tunnel after describing the previous bit "suspiciously clear of dirt and grime" and they'll have a DC15 Perception (not that difficult) to pass before running into it as they round the corner. Even if they make the check, it may engulf a couple in the next round! I did mine right after they hopped down a reasonable climb (say, 30ft) and had a somewhat "Z"-shaped tunnel with the cube at the top of the Z corner. (Note: this is still an "easy" encounter; but it's also still dangerous, if they don't kill it in a couple rounds since it can paralyze/engulf everyone.)

* Have the tunnel be multiple levels that interact. Holes in the floor or weak flooring. Shortcuts that require climbing. "Secret" areas where you'll have to crawl through muck or go around the tunnels to get to; or gated-off areas that they can tell have items but have to go-around to get to.

* Things that get stuck in the sewer: If you have Zombies/Ghouls/etc, finding these in places that the players can fall makes perfect sense. Too dumb to climb really; just sitting there in a pack mindlessly waiting.

* Consider some hazards: Azure Fungus is good; and sprinkling it in various areas gives some push-pull to whether to travel through that area. It's especially useful as a "hazardous terrain" kind of addition to a fight; as the water it's electrifying will be safe for some number of rounds; but the players have to waste time shaving off the fungus or hope they don't get zapped while in the water (or fight only on non-water spots!)

* Could consider Kelpies. Drowning a player in a couple rounds is a pretty brutal way to go; turning an encounter up to 11 in a heartbeat.

* 3rd Party River Troll(basically just a troll with swim.)

* Gibbering Mouthers are suitable to the environment, creepy and weird. Have it rise out of the water after they find themselves "trapped" between a locked gate and it. They have options to fight in this congested area, run passed it as best they can, or attempt to unlock the gate quickly.

* Obvious area to set up a Minotaur; maybe make it large so it's more beastly; and make it a bit more like a puzzle; trying to get the minotaur to charge into things to break them; collapsing a weak part; revealing a new area; bashing through a gate that the party otherwise was going to be unable to get through; etc. This makes the party consider trying to lead it around maybe; before some final conflict with it after harassing them.

I'll note that most of the above encounters are average difficulty; and are more for environmental fun and whatnot.


Douglas Muir 406 wrote:
Oh! Almost forgot: it looks like your group is mostly human, amirite? No gnomes or halflings?

Nah, humans aren't a popular choice here. I don't think I've seen more than one human PC in nearly ten years.

This entire group has darkvision. They are all medium sized, though, so squeezey hazards work.


Mark Hoover 330 wrote:
Also at Dougy Fresh: whoa! So you've got environmental hazards favorable to the otyugh; a mutant aberrant creature ideally suited to said environment; 2 rat swarms on a 1 round delay. The otyugh alone would be a CR 4 encounter. The water, if it becomes a hazard, is a 30' pit so roughly a CR 1; persistent Obscuring Mist/CR 1; each rat swarm is a CR 2; the 4 goblins are between a CR 1 and CR 2; the locked grate likely adds 1 to the overall CR as does the narrow, slippery ledge... I'm figuring a grand total of 3,740 XP in the threats/hazards of the encounter, between a CR 7 and 8, +1 from the ledge and grate, so about a CR 8 - 9 in the end.

Nah it's around a 7. I can play it out if you like, but here's the TLDR: four well played 4th level PCs should have a fun struggle but should not be in serious danger unless the dice turn on them badly. Which is what an APL+3 encounter should be.

Quote:
I am however stealing the "offal dump" encounter for my own game.

Well thank you very much! This idea is not actually mine -- I got it from someone else -- but it was so many years ago that I've honestly forgotten where and from whom.

Doug M.

Dark Archive

Mark Hoover 330 wrote:
Finally, I really enjoy alchemy in sewers. Runoff from labs or workshops in the city mingles with the other muck below. Alchemical ooze swarms, alchemy golems, maybe even any intelligent creature capable of crafting with such volatile substances to harness their power? For this, what about evil grippli? Give them the Toxic Skin trait, plenty of alchemical weapons, levels in Expert and Warrior with a leader with levels in Alchemist, and some oozes and swarms at their command!

Runoff would work great as a hazard. Say there's a thick mist hanging in a section of the sewer. Anyone who inhales the mist must make a fortitude save or be affected by a random effect. The effects are mainly based on transmutation effects, but spells such as Inflict Light Wounds are also a good option. Half of the effects are good, half of them are bad. You only have to roll your fortitude save once. (But don't tell the players that. Let t he PCs hold their breath.)

Somewhere in the vapors are a bunch of mutated Dire Rats. They are all affected by the gas, roll for random mutations. And that's about it. Mutated rats in a cloud of mutagenic gas. I'm sure there are worse encounters. This encounter could lead to a side quest inside an alchemist's lab, so don't use it if you don't need a red herring in your plot.


Quote:
4th level party will be going into the absurdly spacious sewers soon....

Read this thread for campaign ideas.

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