Kassoon

No Prep Module: Demonic Well for D&D or RPGs

This adventure can be can be easily customized to a party of any size or level, or run as a level 2 adventure for 5 players. It can work as a small side adventure in an existing campaign, as a standalone one-shot, or the start of a new adventure. Use the links to the tools in their relevant section to customize the adventure to your party.

Old Well

The hamlet of Peacely is a Halfling town that's also popular with Humans and Elves. It's built around a large fortress, and is known for its mines and industry. Most of the commonfolk work as farmers and miners. There's some tension between the races, with the halflings becoming concerned by the increasing number of outsiders in their town.

Defenses: The hamlet is built outside the fortress walls, but during an attack the populace can move into the courtyard of the fortress (if they're quick enough).

A halfling guard (Myria High-hill) will stop the party if there are any non-halflings in the group and try to deter them from entering the town, asking a lot of questions about their activities and treating them with suspicion. This guard has a soft-spot for gambling and can easily be convinced to allow their passage over a game of chance.

Once in the town, the PCs can learn about how a well was just dug in the middle of town after the old one collapsed. The water smells of brimstone, so the people have refused to drink it, but this has not stopped farm animals from drinking it, and transforming into demonic beasts. To save the town, the well has to be purified and the demonic creatures defeated.

Purifying the water with a spell will only work for a couple hours before it becomes corrupted again. The source of the corruption comes from the bottom of the well, which connects to a demonic labyrinth. Draining the well, swimming to the bottom, or otherwise disturbing it can reveal the entrance to the dungeon. The walls of the well are slick if it's drained, requiring a DC 15 Climb check if they choose to climb down.

Dungeon Map


Enemy Patrol: 2 Manes (CR 1/8: Monster Manual p. 60), 3 Larva (CR 0: Dungeon Masters Guide), 1 Nupperibo (CR 1/2: Mordenkainen's Tome of Foes p. 168), 1 Imp (CR 1: Monster Manual p. 76) [Hard, 380 XP rewarded] [Customize]
Chance of Encounter Per Rest: 10%

Room Contents

You can also generate different descriptions using the Description Generator

1

The great clays of this shaft lead up and down around a 30-foot-wide stone core. Numerous stone columns rise to meet the stone overhead. Nicely cured hide blankets are carelessly strewn over the floor. Worn green drapes cover the windows of this circular room, and a heavy curtain hangs across an archway to the east.

There are 3 Imp (CR 1: Monster Manual p. 76) [Deadly, 600 XP rewarded] here. [Customize]

Each round every living creature gets a stack of Chilling Cold. Any creature with Chilling Cold has to make a Con Save DC 10+X at the start of their turn, taking Xd6 Cold damage on a failure, where X is the number of stacks.

2

Four open wood chests stand against the north wall. A layer of fine dirt coats the inside of the chests and the floor around them. From a distance comes the intermittent echo of organ music. In the center of the northern wall, a space has been cleared for a simple sleeping pallet and a pair of small satchels. Worn yellow drapes cover the windows of this circular room, and a heavy curtain hangs across an archway to the west. The east end of this room has collapsed, exposing the room beyond.

An object in this chamber gives the user the ability to see if someone is nearing death.

3

Thousands of pieces of junk cover the floor. A crisply made bed stands at the middle of the north wall, with long tables off to either side. Two open archways in the west wall lead to another room. The floor just past the first archway gleams wetly. Taut iron chains extend up and down the shaft. The links of the chains are thick and wrapped with grease. Directly across from the stained glass window stands a set of double doors in the south wall.

There are 2 Maw Demon (CR 1: Volo's Guide to Monsters p. 137) [Medium, 400 XP rewarded] here. [Customize]

In the west passage is an unlocked door.

In the south passage (green) is a wall of solid rock that blocks the path.

4

Fine china, old dishware, cauldrons, and shattered crockery covers the floor of this kitchen. Sulfur floats in the air here. Large wood gates hang on the stonework, moss clinging to the bars. A passage to the north bends out of view, while cracked and crumbling wood doors obscure a cavern to the east.

If the hall is searched, they find 23 cp

There is a puzzle: The room is a large square room with four doors on each face, with the party entering from one of them. If they go through any of the doors they’ll find that the doors just go to the opposite side of the room. If they do a WIS DC15 check they’ll find a lip on the floor that belongs to a door that if they swing open will also swing open a ceiling door. The ceiling/floor door does not act in a dual manner though, like the wall doors. What goes down the floor comes through ceiling, but what goes into the ceiling door goes into the exit alcove that leads down a 30’ hallway to the north room (green).

In the east passage is an unlocked door.

In the north passage (green) is a wall of solid rock that blocks the path.

In the south passage (red) is a wide, deep pit that spans the passage with a ruined rope bridge hanging from the side.

5

Doors open to display another set of double doors 30 feet ahead. Between these doors, a 40-foot-wide corridor runs east to southwest. The walls are lined with aged books and tomes, their leather covers well oiled and preserved through careful use. A horrible odor of sulfur fills this steaming hot room. A ravine spills from a cramped crack to the west and crosses the room, disappearing into a precarious, winding tunnel to the east. A door stands closed to the west. The south end of the room ends at a wood door.

There are 2 Screaming Devilkin (CR 1/4: Fifth Edition Foes p. 197), 1 Shadow Mastiff (CR 1/2: Fifth Edition Foes p. 207) [Easy, 200 XP rewarded] here. [Customize]

In the south passage is an unlocked door.

6

Stairs end at the entrance to a round cavern. The floor is inlaid with mossy, dusty green tiles, and the walls are dressed with polished stone. A gate of rough-hewn timber blocks a long passage to the west. The south end of this room has collapsed, exposing the room beyond. Dark, stagnant water pools in the middle of the cavern.

An object in this cavern asks three skill-testing questions (if all three are answered correctly, a reward appears).

7

This 50-foot-square hall is stifled with clutter. Hundreds of dust-laden moss and leaves drape the hall, hiding the ceiling from view. The air here is humid and smells of rot. Double doors of wood stand closed to the east. The mouth of a side cavern leads into darkness beyond.

There are 2 Abyssal Wretch (CR 1/4: Mordenkainen's Tome of Foes p. 136), 2 Abyssal Chicken (CR 1/4: Baldurs Gate Descent Into Avernus) [Easy, 200 XP rewarded] here. [Customize]

8

This long, tight hall is half-filled with an underground crevasse, streaming through at a rapid pace. Dark, stagnant liquid pools in the middle of the hall. The walls here are cracked, and look as if they once supported built-in shelves that have been reduced to rubble. A ramshackle bed with a tattered canopy stands nearby. Farther away, a solitary door leads from the west wall. The tunnel splits ahead, with one branch running north and the other continuing on to a lit hall.

In the north passage (red) is a wide, deep pit that spans the passage with a ruined rope bridge hanging from the side.

9

Faint light filters into the hall through the steel lattice squares of four headed glass windows. From the dark shadows amid the rubble, two pairs of black eyes stare back at you. Moldy wood posts struggles under the weight of the wood ceiling. A door stands closed to the south. A gate of rough-hewn timber blocks a long passage to the north.

In this hall is a trap. A fragile glass orb is precariously perched on a pedestal at the end of a hallway. Strong enough vibrations can cause the orb to fall and shatter, triggering the trap that causes webbing to shoot out of small holes in the walls, sticking to anyone in the area.

Effect: Targets all creatures within a 20 ft. square area, webs shoot out and fill the area, DC 10 DEX save or restrained until a DC 10 STR save is made to break them free.

Trigger: shatter, activates when a precariously balanced glass orb falls and shatters.

Countermeasures: A spell or other effect that can protect the orb from shattering, such as feather fall, will disarm the trap. A successful DC 10 Dexterity (Sleight of Hand) check will carefully remove the orb without breaking it. Disruptive effects like combat or running will vibrate the orb and cause it to fall.

The webs can be set on fire to burn them away. Any creature within the burning webs takes 7 (2d4) damage per turn. Plugging the holes with cloth or other material will prevent the webbing from firing. [Customize]

10

The gap running along the mine meanders through a natural cavern before tumbling into a great chasm. A wood door in the north wall is carved with a dwarf's visage. The furnishings are covered with bloodstains and moss and leaves, lying in anarchy. This immense cavern is a place of chilly, brooding blackness. The south end of the cavern ends at a wood door.

In this cavern is Violet Fungus: This purplish mushroom uses root-like feelers growing from its base to creep across cavern floors. The four stalks protruding from a violet fungis central mass are used to lash out at prey, rotting flesh with the slightest touch. Any creature killed by a violet fungus decomposes rapidly. A new violet fungus sprouts from the moldering corpse, growing to full size in 2d6 days.

11

The short ceiling of this 40-foot-square room presses down on you. This room is full of pretty little dolls with tanned skin and blonde hair, some of them dressed beautifully, others plainly. Shields and swords jut from the walls as if driven into them by some tremendous force. Ten-foot-square cells, their entrances blocked by iron bars, outline both sides of the room. A pair of leaded glass doors, their panes cracked and broken, stand open between panels of stained glass set into the south wall. These panels depict illithids. A gate of rough-hewn timber blocks a lengthy passage to the north.

If the room is searched, they find 14 cp

In the north passage is an unlocked door.

In the south passage is a locked door (DC 15). Key could be found on a nearby creature or furniture.

12

This room has a 5-foot-high ceiling and a large green well on the wood floor. Immense doors of iron-bound mahogany exit to the north and south. From the black shadows amid the rubble, four pairs of red eyes stare back at you. This chamber stands in deadly silence.

There are 4 Lemure (CR 0: Monster Manual p. 76), 2 Manes (CR 1/8: Monster Manual p. 60), 1 Shadow Mastiff (CR 1/2: Fifth Edition Foes p. 207), 1 Imp (CR 1: Monster Manual p. 76) [Hard, 390 XP rewarded] here. [Customize]

In the north passage is an unlocked door.

13

This 35-foot-square chamber is in shambles. Within this area lie ancient catacombs, with arched ceilings supported by wide, hollow columns that double as crypts. A barricade stands closed to the north. Past the chamber, the hallway turns back to rough stone and turns to the south.

To the south (pink) is a secret passage

14

The walls are lined with crumbling books and tomes, their leather covers ruined and dusty through misuse. The aromas of animal musk and well-oiled wood hit your nostrils as you enter. Barely contained within this chamber is a round tower, 20 feet on a side and 10 feet high, with arrow slits on all sides and a battlemented roof. Two open archways in the north wall lead to another chamber. The floor just past the first archway sheens dankly.

If the chamber is searched, they find 16 sp

In the north passage is an unlocked door.

15

You can hear the distant sound of distant battle and wailing coming from far below. Thick beams sag overhead from centuries of supporting weight. Hanging from a wood rod bolted to the southern wall are muddy, ten-foot-square wide webbing. The floor is littered with a table and animal hides. Sculptures and pottery are arranged about the hall. Piled around the hall are chairs, skins, rubbish, and old shelves dressed with vines and dust. Two open archways in the north wall lead to another hall. The floor just past the first archway gleams wetly. A pair of leaded glass doors, their panes cracked and broken, stand open between panels of stained glass set into the east wall. These panels depict driders.

There are 2 Abyssal Chicken (CR 1/4: Baldurs Gate Descent Into Avernus), 1 Nupperibo (CR 1/2: Mordenkainen's Tome of Foes p. 168) [Easy, 200 XP rewarded] here. [Customize]

There is a puzzle: A mirror that shows a reflection of the room the players are in, however, the reflection happens to have one extra item in it. The players must find this item and place it in the correct location in the real room. Solving the puzzle causes the rope bridge to magically repair at the red passage.

In the east passage (red) is a wide, deep pit that spans the passage with a ruined rope bridge hanging from the side.

16

The cavern is unlit and stinks of grease. Tarnished, blacked lace hangs neatly from eight canopied beds. Broken glass and the remains of shattered tables cover the floor in the dry section of the cavern. Thrones sit away from the double doors that give access to the cavern. Two open archways in the north wall lead to another cavern. The floor just past the first archway glints humidly. Cut into the wall is a small but strong-looking door of iron plates, about five feet tall and four feet wide. Thick rivets stud its surface, and a tarnished silver rune gleams on the door’s rusted face.

There are 2 Manes (CR 1/8: Monster Manual p. 60), 1 Abyssal Chicken (CR 1/4: Baldurs Gate Descent Into Avernus), 1 Kalke (CR 1/4: Tome of Beasts p. 259) [Easy, 150 XP rewarded] here. [Customize]

In the west passage (red) is a wide, deep pit that spans the passage with a ruined rope bridge hanging from the side.

In the north passage is an unlocked door.

17

Wailing seems to travel the length of the passageway as it rises and falls. Water trickles through cracks in the ceiling, streaming down the west wall and adding to a large puddle on the floor. Two open archways in the west wall lead to another hall. The floor just past the first archway shimmers moistly. Mahogany paneling decorates the walls to a height of four feet. A set of slender stairs cut into the rock wind up to the north, and two old wood doors stand in a wall of dressed stone to the east.

There are 2 Abyssal Chicken (CR 1/4: Baldurs Gate Descent Into Avernus), 1 Nupperibo (CR 1/2: Mordenkainen's Tome of Foes p. 168) [Easy, 200 XP rewarded] here. [Customize]

To the north (pink) is a secret passage

18

Heavy posts hold the ceiling of this small chamber, with a curved outer wall. The door to the south and west are sheathed in stone. Broken bones lie strewn amid crumpled and crushed cloth armor. The area smells of animal musk. The mouth of a side room leads into blackness beyond.

In this chamber is a trap. Targets all good creatures that touch it, DC 14 WIS save or take 10 (2d10) damage

Trigger: touch trigger, activates when surface is touched by a creature.

Countermeasures: A spell or other effect that can sense the presence of magic, such as detect magic, reveals an aura of divination magic around the surface. A successful dispel magic (DC 14) cast on the surface destroys the trap. [Customize]

In the west passage is an unlocked door.

In the south passage is an unlocked door.

19

From a distance comes the intermittent echo of a dark buzzing. Dark, stagnant slime pools in the center of the cavern. A few insects zip about near the top of the 40-foot-high vaulted ceiling. Four dretches are sitting around a table, playing cards for copper pieces. Many tomes and scrolls lie sprinkled on the floor, around two heavy wood chests fitted with iron locks. Attached to the south wall is a steel plate that has an stone lever protruding upward. Ragged blue drapes cover the windows of this circular room, and a heavy curtain hangs across an archway to the north.

Imp Demon

With the demons cleared out, the well's water is purified and the villagers can use it again. For their help, the PCs are rewarded with 100gp. However, a few days later another animal turns into a demonic beast, revealing that it wasn't the well that had been transforming them at all. Some other force in the town is responsible, leading possibly to a campaign to find the true culprit and uncover the nefarious plot of the nobility.

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