A review copy of “Undermountain: The Lost Chambers” was provided by the publisher. Find more DMs Guild Reviews on my website and YouTube channel.

Support my work via Patreon.

Published by: Pyromaniac Press (with Phil Beckwith, Alex Clippinger, Elise Cretel, Ashley May, Luciella Scarlett, Christopher Walz & Micah Watt)

dms guild reviewWaterdeep: Dungeon of the Mad Mage is absolutely massive. Yet it’s also ripe with opportunity for even more dungeon-crawling adventures, thanks to numerous dead ends and off shoots in each level. “Undermountain: The Lost Chambers” provides nearly a dozen such locations from seven different DMs Guild authors.

The mini-dungeons could easily be dropped into any underground or underdark area, with most acting as boss monster lairs or divine shrines. It’s a solid variety, though most of the actual connections to Dungeon of the Mad Mage are tenuous at best.

“Undermountain: The Lost Chambers” features 11 mini-dungeons of around six rooms each, ranging from level 3 to 13, though most fall squarely in the Tier 2 range (5-10).

Each author has designed 1-2 mini-dungeons, with most of them resulting in combat-heavy monster lairs. That’s not necessarily a bad thing and most are quite inventive and interesting, from a fungus-drenched laboratory full of zombified myconids to an Ultrathid hideout featuring an imprisoned aboleth.

The few areas that include actual NPCs are mostly underwhelming, including a weirdly intelligent goblin mage who speaks proper Common with zero explanation as to why, and an odd encounter with a flying machine that results in the party gaining a dimensional-crossing Leonardo Davinci ally.

The best use of role-playing is with the humorous Undermountain Water Purification & Sanitation area, featuring a bossy and befuddled gnome and a bunch of modron sewage workers fighting off some lizardfolk who have recently moved in. The whole situation can be solved without lifting a sword.

dms guild

For the rest it’s all about the smash and grab, but there are some really fun moments to uncover. I particularly enjoyed the gargantuan gelatinous cube in Hunger of Abbathor as it drops in behind the PCs, cutting off their exit and pushing them inexorably toward the edge of a cliff where the giant head of a dwarven god looms (complete with mouth chute). And the entrance to the Ultrathid lair in Of Two Minds features an intriguing trap involving prisoners and intellect devourers, and the climax involves a battle of psionics between the Ultrathid and a captured aboleth. That whole dungeon is probably my favorite of the bunch, packing a lot of fun moments into a small area.

I very much appreciate that every single dungeon is given a tactical, detailed, grid-based battle map (save one, which has an isometric design – lovely but not practical). On the flip side, only the embedded DM map with annotations are included. We need separate player maps please!

The mini-dungeons lean a bit heavily on the combat side, but most remain memorable and worth exploring, and fit very well into both Dungeon of the Mad Mage and Out of the Abyss campaigns – or any large underground area that could use some interesting offshoots full of gibbering demons, forgotten gods, and other denizens of the dark.


  • 11 mini-dungeon crawls (with full color grid maps!) that can be easily dropped into any larger dungeon or underground area.
  • Level scaling for every combat encounter.
  • The UWPS is a hilarious idea with lots of fun role-playing opportunities.
  • Off Two Minds, The Hunger of Abbathor, Abandoned Atelier, and the Cathedral of Bones are all stellar monster lairs.


  • Lacks separate player maps.
  • Several themes and enemy types overlap, particularly the mind-controlling illithids and aboleths.
  • Few actual ties to Dungeon of the Mad Mage.
  • Requires Volo’s Guide to Monsters, Mordenkainen’s Tome of Foes and Tomb of Annihilation to use every monster stat block, with no alternative suggestions.

The Verdict: While it mostly lacks meaningful ties to Dungeon of the Mad MAge, “Undermountain: The Lost Chambers” does feature several solid mini-modular monster lairs for any underground area.

A review copy of “Undermountain: The Lost Chambers” was provided by the publisher. Find more DMs Guild Reviews on my website and YouTube channel.

Support my work via Patreon.