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Dungeons
Sewer · Small · Level 2 · Easy

Floodgate Sewer Den

In the flood tunnels below the city, claws, rust, and old grudges wait in the dark.
Rooms
4
Foes
4, CR 1/4 to 1
Traps
1
Treasure
125 gp
1234Entrance
Select a room on the plan to open it.

The party is in

1. Sump Watch

Seen

Something wanders by

At a glance

The threat

The lizardfolk defend their stolen lair with territorial fury, but the deeper danger is the rust monster lurking in the drainworks.

Wandering monsters (1d3)

  1. 1

    Lizardfolk HunterCR 1/4

    When: Triggered by loud combat or prolonged searching in the corridors.A lone lizardfolk hunter stalking the corridors for intruders or strays from the main lair.
  2. 2

    1d2× Sewer ScavengerCR 1/2

    When: Triggered when the party disturbs the runoff channels or opens a locked door.A skittish sewer scavenger dragging a sack of scrap and bones, desperate to flee rather than fight.
  3. 3

    Young Rust MonsterCR 1/2

    When: Triggered by clanking armor, dropped weapons, or opening the maintenance grates.A small, hungry rust monster sniffing for iron fittings and unattended weapons.

Rooms

4
1

Sump Watch

2 foestreasuresecret

What they see

Read aloud

A low, brick-lined chamber where dry stone ledges ring a central runoff channel. Fresh claw marks and fish bones show the lizardfolk have claimed this as a watch post, and muddy footprints lead toward the deeper rooms.

Features

  • Slick stone ledges
  • Central runoff channel
  • Mounded fish bones
  • Scattered reed mats

What the GM knows

Monsters

2× Lizardfolk ScoutCR 1/4

Lean sentries with bone spears and hide shields, wary but not eager to die.Tactics. They fight from the ledges, use the channel as cover, and retreat toward if badly hurt.

Treasure

Mud-Stashed Coin Pouch18 gp

A pouch of mixed copper and silver coins hidden under the reed mats.
Room secrets · GM only

Notes

Use this as the first read of the dungeon. The scouts are alert to sounds from and may warn the boss if the fight lasts more than a round or two.

3 doors: S (locked), W (normal), E (locked)

The place

What it is

This small sewer complex has been seized by lizardfolk scavengers who turned the old maintenance chambers into a lair.

Atmosphere

The sewer tunnels are damp, narrow, and sour with old waste, algae, and the metallic bite of rust.

The threat

The lizardfolk defend their stolen lair with territorial fury, but the deeper danger is the rust monster lurking in the drainworks.

History

These sewers were built beneath an old riverside quarter to drain floodwater and industrial runoff.

Rumors

1d4
Roll a rumor

  1. 1The sewers are haunted by lizardfolk that wear watch badges as trophies.
  2. 2Something in the drains can eat iron fast enough to ruin a sword in seconds.
  3. 3A city worker vanished near the floodgate, but his lantern was found neatly stacked in a dry chamber.
  4. 4There is a hidden vault below the sewer where the old district's emergency supplies were stored.

Plot hooks

3
cleanupThe Gate Is FailingA city guard asks the party to clear the sewer before the rust monster eats the iron gate that protects the riverside market.From: Captain Veyra HoltReward: 25 gp each and official favor with the city watch
rescueStolen in the SlimeA terrified tanner claims the lizardfolk stole a family signet and hid it below the drains.From: Milo Grent, tannery foremanReward: A silver reward purse and a masterwork tool kit
recoveryLantern in the DarkA shrine keeper wants the party to recover a blessed drain-lantern lost in the sewers before it is melted by corrosion.From: Sister AlwenReward: Healing potions and a minor blessing

Corridors

4

  • Between and

    Waist-high runoff channels carry slow gray water, forcing careful footing and leaving slick moss on the walls.

  • Between and

    Bent iron grates in the floor hiss when stepped on, venting warm, foul air from deeper drains.

  • Near and

    Scratched lizardfolk glyphs mark safe ledges, hidden routes, and a warning sign for intruders.

  • Throughout the dungeon

    Rust freckles the brickwork in broad orange stains, and any metal left here too long feels gritty to the touch.

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