Sewer monsters?

[Rechan]

If you have a Libris Mortis, a sewer could be an interesting place for undead with the swarmshifter template. I can just see several swarms of undead flies or rats transforming into a ghoul pack.

Here's a suggestion for Swarmform: Give the undead regeneration but a weakness for fire.

Why? Every time the undead receives a hit, bugs fly off of them, and then flit back into the wound.

 

[Darklone]

Cannibalistic halflings. I have them in almost every sewer.

 

[the Jester]

Unique to Golarion (the setting of Pathfinder) in its sewer association, but something I really like: derro. In the setting, derro are the little blue men (think aliens, not Smurfs). They abduct people at random, drag them underground, paralyze them, conduct horrible and inconceivable medical experiments, then return them hours or days later.

swipe

 

[TheAuldGrump]

The only problem there is that the image will likely be lost or unappreciated; PCs would more than likely just blast it as it's crawling out of the pipe than watch.

(Unless the thing can move real fast).

It is a second level party - with even a little bit of beefing up (character levels, etc.) It can easily survive two rounds or so of squeezing out of the pipe. Put the pipe up high, and allow Notice checks to see if the PCs catch a glimpse while it is oozing out, and before it drops down on its prey.

The Auld Grump

 

[Orius]

Not only could you find criminals down there but the sewers would be a perfect spot for a hidden shrine or temple to a forbidden god. Especially the disgusting ones.
Maybe the PCs somehow stumble in just as they're about to sacrifice some poor sap.

Juiblex sounds like a good candidate.

 

[hong]

Jubbliex?

MACHINE-GUN Jubbliex, BAY-BEE?

 

[diaglo]

A poo elemental.

Like this one.

mudmang

shambler

rot grubs

violent fungi ... relative of the violet fungi but meaner.

shriekers too.

 

[SiderisAnon]

Kobolds, of course, because they're perfect for hiding out in cramped sewer tunnels.

Old undead that someone forgot about.

A sentient potion that lives in a pool under the drains from the Street of Alchemists.

The Sewer Rats of Nimh (sp?) living under the Wizard's Guild.


I also once had an encounter where the party came across a group of goblins banging on a pipe in the mostly dark. The party immediately attacked everyone and everything, not even stopping to figure out what was going on. Turns out a pair of sewer workers had enslaved the goblins and were using them to do their work, while the two humans oversaw.

Once the paladin in the party realized he's just struck down two legitimate city employees without a second thought, he immediately used his healing to save one, but the other was too far gone. The paladin set up a fund to care for that man's family as part of his penance. (All the paladin PC's idea too. I didn't have to actually assign him any. He came up with his own list and went to it.)


There's also the old standby of a gleatinuous cube.

 

[Rechan]

Here's an idea: sentient plant.

Something that could survive with the low lighting. Perhaps its roots come in from above. But for some reason, I think it'd be hilarious to have some talking creature like Little Shop of Horrors. Maybe with some followers, or a makeshift "court" as it were of sewer denizens.

 

[Arkhandus]

A few dire rats with the Phrenic template...some 1 hit die, one or two of 2 HD, and one with 3 HD. Call them Cranium Rats.....muhahah. They'll freak when one of the rats starts attacking their minds and the others appear to be protected by short-lived forcefields.

But you absolutely must have a poo monster of some sort. Justice demands it! ....okay, really just I demand it.