Secret Lair of the Demented Thaumaturge

Secret Lair of the Demented Thaumaturge

The Dungeon


Are you playing Anomalous Subsurface Environment? In Fifth Edition? And did Terry and Phil steal your characters’ sick rock? Did they also sell it in a city and did you use Wyrd Ways of Walstock for that? Do you want to expand the dungeon beneath the hospital so that instead of a demonic snake there’s an ancient super-science machine powered by said sick rock?


Well have I got something for you!


Secret Lair of the Demented Thaumaturge is a dungeon for characters of level 1-2, featuring a mad scientist’s underground laboratory slash hospital. I did a search for mad scientist-based adventures for my game and couldn’t find any, so I whipped this one up myself. Thanks to Jeff Rients for his how-to guide in Fight On! magazine.


  • The party’s sick rock has been stolen and sold to a crazy person! We need that to open the gates to the megadungeon!
  • An NPC someone cares about has gone missing and all clues point to that quack dr. Kurt Benzo!
  • Healing magic in the city is losing its potency – while the methods of the cult of science continue to function. Foul play is suspected!
  • People all over town are getting sick and dying – is some terrible poison leaking into the water through the sewers?
  • The church of science has not heard from this chapter of its society for weeks. What if something happened? What if they’ve stopped pressing the button??

Dungeon Features

The underground complex is lit by torches, although there is a basic power network (powered by the generator in area 5) that powers electrical lights in the two wards (areas 7 and 9), Benzo’s lab (area 14) and the pyramid room (area 2). The floors are marble, but close inspection shows that this is merely a thin veneer made to look like marble. The walls are covered with an ancient glass-like substance, perfectly smooth to the touch.


Rooms are 20’ high, hallways 15’.


Alterations to Magic. The infernal machine disrupts nearby magic, particularly healing magic. Any healing spell heals for half the normal amount of hit points.

Monster Key

Instead of creating a host of custom monsters, existing ones can be reskinned. Here’s a list of monsters used with their “normal” counterpart:



Is Really A


cultist (they look innocent enough until the stabbing starts)


hobgoblin (hospitaliers are human knights with a deadly syringe-like spear, which uses the hobgoblin’s martial superiority damage)


acolyte (they use the power of science instead of prayer to power their spells, of course)



greater mutant

ghast (but not undead and without paralyzing claws)


Random Encounters

Roll for a random encounter whenever the party makes a lot of noise or decides to do a thorough search of a room for treasure/secrets (consider allowing them to find secrets and treasure as if they rolled a 20 on their Perception check in this case). Random encounters occur on an 18+ on a 1d20.





1 doctor + 1 hospitalier


3 nurses


The greater mutant has escaped from area 13!


6 baboons


2 guards + 1 mastiff


1 spy, sent to investigate the area (pick a motivation from the Dungeon Hooks)



1. Entryway

Signs. Four metal plates hang from the ceiling, one below the other, connected by thin chains. They read:



⇐ (north): CARDIOLOGY

⇒ (south): RADIOLOGY

⇓ (west): EXIT


Patrol. The generator and patrol from area 5 can be heard here by a careful party and can hear a careless one, or stumble into characters that linger too long.

2. Pyramid

A 10’ tall pyramidical structure dominates this room, a soft red glow emanating from its top. In the corner lies a pair of 8’ high stilts. A curtain depicting a snake wrapped around a rod decorates the southern wall.


Stilts. The bottom 3’ of the stilts are white as if bleached.


Pyramid. The eastern section of the pyramid has stairs worked into the layers, allowing easy ascent. However, one of the bottom steps is a pressure plate that causes a spray of acid to erupt knee-height from the next ledge (1d10 damage, DC 12 Dex save for half). On top of the pyramid is a counter which decreases every second. It reads “615496”. Pressing a button next to the counter resets it to “2.628e+6”.


Curtain. The snake-curtain barely hides the passage beyond.

3. Library

Two bookshelves stand against the walls of this room, and a trio of small wooden benches are neatly placed before them. Most of the northern wall is covered by a curtain depicting three overlapping thick blue bars.


Bookshelves. Amidst hundreds of tomes filled with the writings of a mad man are 4 ancient texts. Each page has a thin transparent film protecting it from the ages and shows a detailed drawing of human anatomy. To a collector, they are worth 25 gp each.

4. Specimen

Glass cylinders filled with a thick, clear liquid run floor to ceiling. A monstrous body floats in each. The southern door is made of a greenish-black metal.


Cylinders. The corpses stare blankly from behind their glass vessels. Their faces and bodies are distorted, skin pulled taut over deformed bones. Protruding jaws make them look more like animals than men.


Metal Door. The door is made of protonium, a rare metal that is completely impenetrable. It is currently locked and cannot be opened save for digging through the surrounding walls.

5. Generator

Generator. A black housing surrounds a highly efficient antique double cylinder steam engine, which can run for a day on a single pint of oil. It powers the artificial lights in the dungeon and if destroyed (or disabled) reduces visibility to dim light. The device is temperamental, so its disruption might not cause immediate investigation. Note that the machine in area 14 has its own built-in emergency generator.


Patrol. A patrol consisting of 1 hospitalier and 1 guard, accompanied by a bullmastiff lingers here. The machine’s noise shields intruders from detection, although it merely cancels out the dog’s Advantage on Perception checks. The patrol wanders between this area and areas 1 and 6.

6. Offering Chamber

The wall is covered by a 15’ x 20’ tapestry. It shows stylized images of medicinal practices.


Tapestry. The images start with well-known and proven techniques such as blood-letting, leech therapy, and trepanation, and moves towards more and more fantastical procedures such as metallic spiders burning wounds using focused rays of light. The tapestry is an ancient masterpiece and worth 250 gp. In a bowl in front of it lay offerings of dead snakes and silver coins (120 sp).


Secret Door. The tapestry distracts from a not-so-subtle secret door (automatic detection if anyone cares to search) in the western wall which smoothly pivots into the small corridor beyond when force is applied.

7. North Ward

Twelve cots, each with a small bedside stand, are regularly spaced across the room. Five are filled. Three nurses are tending to the patients.


Patients. The men and women in these beds are grossly deformed with elongated limbs, patches of sickened, scaley skin, and snarling visages with contorted, misshapen jaws. These poor souls are all, unfortunately, beyond saving. Four are left in a permanent coma. One, still conscious but sedated, is restrained to the bed by leather straps. If this mutant gets a chance it will rip itself free and attack without prejudice.


Stands. Rummaging through the stands unearths private items of the patients. Of note are a golden ring (15 gp), an agate hairband (25 gp), and a prayer bead with quartz stones (25 gp).

8. Connector

Signs. Two metal plates hang from the ceiling:


⇒ (north): NORTHERN WARD

⇐ (south): SOUTHERN WARD


No sign points towards the eastmost exit, but the door has a sign hanging on it that informs would-be-visitors to “do not disturb”.

9. South Ward

A doctor and nurse tend to a number of patients spread across 6 cots. One guard oversees the activity. The doctor wears a golden amulet of a snake around an iron rod (25 gp, which can be used as a spell focus).


Patients. All are disfigured as in area 7, and non-responsive*.


Stands. A golden locket with a portrait (25 gp) and a pair of moonstone earrings (50 gp) can be found among useless personal trinkets.

10. Back Area

The room is filled with piles of rubbish, discarded clothes, broken furniture, rubble, glass, and other detritus. A skeleton lies face down on the floor, its bones picked clean.


Corpse. An unfortunate adventurer lies here, weakened from the sludge in the southern room, and finished off by the rats.


Rats. A group of 4 rats and 1 giant rat nest under an especially large pile of trash. They won’t attack if outnumbered but will try their luck on any stragglers.


Door. The door to the north is locked but can be picked or forced open easily (DC10).


Tunnel. The giant rat has tunneled to the east and into area 12. The tunnel is large enough for a medium-sized character to crawl through and is hidden behind a pile of stained sheets.

11. Sludge Pool

A stream of waste pools in this room from pipes emerging from the eastern wall, before flowing out into the sewers.


Pool. The waste is tainted by the device in area 14, which can be seen as a sickly shine but only to those who have darkvision. Stepping into the water briefly is fine, as its effects won’t penetrate boots, but if a character touches skin to water they must roll a DC 20 Con save or lose 1d4 points of Constitution, until healed by a cure poison spell or similar. There is no nonmagical cure. A character who drinks the water endures the same effect (no save) and suffers from the poisoned condition until cured.

12. Serpentarium

Four wicker baskets stand against the wall, each with a lid with a heavy stone woven in for weight. A cabinet stands against the southern wall and contains various small flasks.


Baskets. Two of the baskets each house a live poisonous snake.


Cabinet The cabinet holds 6 antitoxin potions. If moved it reveals a small tunnel that ends up in area 10.

13. Observation Room

The room is split in two by a wide one-way mirror, which allows the northern side to peer into the southern side, where a greater mutant is trapped among the trashed remains of wooden chairs and tables. Leather straps are attached to some of the debris, and various medical implements lie scattered around the floor. The northern side, which is raised 5 feet over the southern, has a neat pair of small chairs, each with a side table containing notes.


Mirror. The mirror resists attacks but can be smashed with concentrated effort and suitable weaponry. Using a hammer and piton or similar shatters it instantly. Otherwise a random encounter roll might be in order.


Detritus. A search of the southern room retrieves a set of protonium medical tools. These unbreakable and eternally sharp tools provide a +1 bonus to Medicine checks and can be sold for 250 gp.


Notes. The notes tally experiments followed by either a cross or a check-mark. The nature of some of these is explained by handwriting in the margins: sleep deprivation, injecting snake venom, and force-feeding were-rat meat are some of the ones that seem to have succeeded.


Door. The southern door is locked from this room, though it can be opened easily from outside. It has a hatch that can be opened from the hallway to peer inside.

14. Inner Sanctum

Doctor Kurt Benzo, Ph.D., mans the machine in this room. The circular southern area is raised and surrounded by terminals, buzzing cabinets, flickering lights, and multitudes of buttons and levers. Four thin pillars, each holding a charged amber gemstone, are wired into the mainframe. Small copper plates adorn the walls. Behind a glass window in the central cabinet, a fist-sized chunk of black stone glows faintly. The room smells clean, chlorine-like, but burnt, and crackles with static electricity.


Benzo is a priest of the cult of science, which observes a methodology characterized by dogmatic adherence to ritual and a profound lack of actual knowledge. Still, the latent power of his repurposed ancient technology, coupled with his absolute lack of ethical inhibitions, has led to some breakthrough discoveries. If combat ensues, Benzo activates the machine to cast a spell; call lightning would be a thematic choice.


Activating the Machine. The machine acts like a sinkhole for magical energy – disrupting spells in the city above. This energy can be released to copy the effect of any 3rd level spell. The members of the cult ascribe this to the power of science, and not magic, which would be heretical. After using the machine it needs to recharge for 24 hours.


Copper Plates. The copper plates are angled towards the center of the platform to channel the machine’s magic. There are 400 in total, each weighing 1 pound and having a value of 50 cp.


Sick Rock. Each turn that a character spends in contact with the rock, that character makes a DC 20 Con save or loses 1d4 points of Constitution until healed by a cure poison spell or similar. There is no nonmagical cure. Just being within 10 feet of this thing requires a DC 15 Con save to avoid being poisoned for 10 minutes.


Protonium Door. The door to the north can be opened from this side.


Secret Door. The secret door opens with a flick of a button. The hallway outside has a similar button, although it is hidden behind a loose stone.


Treasure. The copper plates are worth 200 gp. Each amber gemstone is worth 150 gp. There is a large, thick, leaden box in a desk drawer. It can safely transport sick rock. It weighs 20 pounds.




* This writer is aware that the easy way out has been taken with the patients. Feel free to furnish them all with elaborate personalities and backstories!

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