Our twenty-fifth downloadable GM-SS Dungeons and Dragons One Shot Adventure – a dungeon crawl so brutal, you need to GMs to run it!

Whether it’s for a one-shot adventure, starting a longer story, or just another day in your players’ lives, we hope this adventure module will inspire all you DMs and GMs out there. Our twenty-fifth adventure sends your party into the bowels of an ancient factory. Weird alchemical concotions and powerful constructs will test both their mind and metal. Enjoy!


  • RPG: D&D 5e

  • Number of players: 4-8

  • Recommended level: 6-7

  • Duration: medium (4-8h)

  • Difficulty: Deadly

  • For your campaign: This is one shot is designed to be played with two GMs working in parallel, with the parties being separated at the very beginning of the dungeon. However, the adventure can be run by a single party and DM, by just alternating the rooms of each path. Of course, this also doubles the length of the adventure.

  • This Adventure Module contains: 

    • The story for a short and brutal dungeon crawl
    • Guidelines on how to run a one-shot adventure with 2 game masters
    • Several battle maps of an abandoned factory
    • Builds for several new monsters and fights
    • New mechanics and status conditions revolving around two ancient substances
    • A two-phase final boss battle that puts the party’s wit to the ultimate test

The Story

Artificers, arcanists and common tinkerers know the name of Aeron Thrand. Not only because of his generous patronage of their businesses, but also for his constant insistence, that current craftsmen were merely creating pale imitations of the “true arcane mechanics” achieved by cultures past. To prove this bold hypothesis, the self-proclaimed “inventor genius” had used his inherited wealth to found a town called “Aeoria” in the middle of nowhere. Although initially ridiculed as a rich man’s eccentric fantasy, the town soon attracted gifted craftsmen from all over the continent. This was of course due to the horrendous amount of money Thrand poured into the construction of workshops, but also due to his relaxed stance on research ethics. With him as mayor and sole authority, anybody not judged as worthy was forever exiled from the town. Despite or maybe because of his ruthlessness, weapons and mechanical wonders made in Aeoria were soon coveted goods amongst nobles and armies alike. Yet, Aeron Thrand was not satisfied. He spent his days creating digging machines in his remote open-air workshop, clearly looking for something specific. Each day, more tunnels were dug and Thrand’s temper grew darker. Finally, the digging noises stopped, and a single message was sent out through Thrand’s vast supply chain: “Looking for Heroes of the Realm, High Danger, Grandiose Reward”.

In this 4 to 8-hour one-shot adventure, a party of 6th level characters are hired by Thrand to retrieve an artifact from a recently unearthed ruin. Can the players navigate this ancient mechanical dungeon, or will they be crushed beneath its “Gargantuan Gearworks?”

Notes for the GM / DM

  • This one-shot takes a lot of preparation on part of the two GMs – so it is recommended for both GMs to fully read the entire document.

  • The adventure can be lengthened further by introducing additional encounters with the many constructs of the factory (provided in the appendix).

  • The final fight takes up almost as much time as the beginning of the adventure. Hence, this adventure is better for players used to fighting large battles.

GM-SS 25 Cover