Toxic Mine

Mine
Partonez, CC BY-SA 4.0, Wikimedia Commons

The land itself is poisoned. Yellow water stands in the hollows, the air stings the eyes, and the few plants that still grow are bitter and oddly coloured. Whatever lives here has learned to live with poison, or carries it. Shafts and galleries dug by people after ore, coal, salt or stone. Dark, cramped and dangerous, with bad air, flooding and falling rock, and the work of generations in its walls.

Hear it

For the table

Ground
hard going, about 10 km a day on foot
Water
by season
Foraging
nothing

Hazards

  • Darkness. No daylight at all: every step needs a light, and every light burns out. A party without spare torches or oil is blind.
  • Bad air. Low pockets of foul or burning air: lamps gutter, then miners faint. Miners carried a flame, later a bird, to tell.
  • Falling rock. Frost, rain or a careless step bring stones down from above. Scree slides underfoot.
  • Rising water. Rain outside fills passages within hours. A way in can become a sump.
  • Poisoned water. Springs and pools look clear and taste of metal. Boiling does not clean them.
  • Choking vapours. In still hollows the vapours pool, heavy and unseen. Birds that land there do not fly off again.
  • Caustic mud. Some patches of mud bubble and smoke. They eat through leather in an hour, and through skin faster.

D&D 5e

Plays as
Underdark, normal pace at most
Checks
forage: Survival DC 20 · find the way: DC 10 · search: DC 20
Creatures are spotted at
2d6 × 10 ft
  • Darkness. Darkness is Heavily Obscured: a creature trying to see into it is Blinded. Dim light is Lightly Obscured. Darkvision turns darkness into dim light within its range, in shades of grey.
  • Bad air. A creature that cannot breathe holds its breath for 1 + its Constitution modifier minutes (at least 30 seconds), then gains 1 Exhaustion at the end of each of its turns until it breathes again; that Exhaustion goes once it does.
  • Poisoned water. (House rule) A creature that drinks the land’s water, boiled or not, makes a DC 13 Constitution save or has the Poisoned condition for 24 hours. Only water carried in, or made pure by magic, is safe.
  • Choking vapours. A creature in the vapours must hold its breath, for 1 plus its Constitution modifier minutes (never less than 30 seconds). After that it gains 1 Exhaustion level at the end of each of its turns, and loses them all as soon as it can breathe again.
  • Caustic mud. (House rule) A DC 13 Wisdom (Survival) check spots a patch before anyone steps in. A creature that steps in makes a DC 12 Dexterity save or takes 2d6 Acid damage, and its boots are ruined.

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

Pathfinder Second Edition

Plays as (Pathfinder Second Edition)
underground, difficult terrain, about 16 km a day at Speed 25
Checks
Subsist: Survival DC 40 · Sense Direction: Survival DC 20
  • Falling rock. An avalanche, landslide or collapse deals major or massive bludgeoning damage (8d6 to 24d6); a Reflex success halves it and a critical success also avoids burial. Buried creatures take minor damage each minute and are dug out with Athletics (GM Core p. 96).

This product is licensed under the ORC License located at the Library of Congress at TX 9-307-067 and available online at various locations including paizo.com/orclicense, azoralaw.com/orclicense, and others. All warranties are disclaimed as set forth therein. Attribution: this rules layer is based on the following Licensed Material: Pathfinder Player Core © 2023 Paizo Inc., Designed by Logan Bonner, Jason Bulmahn, Stephen Radney-MacFarland, and Mark Seifter. Authors: Alexander Augunas, Kate Baker, Logan Bonner, Jason Bulmahn, Carlos Cabrera, Calder CaDavid, James Case, Eleanor Ferron, Steven Hammond, Joan Hong, Vanessa Hoskins, James Jacobs, Jenny Jarzabski, Erik Keith, Dustin Knight, Lyz Liddell, Luis Loza, Patchen Mortimer, Dennis Muldoon, Stephen Radney-MacFarland, Mikhail Rekun, David N. Ross, Michael Sayre, Mark Seifter, Kendra Leigh Speedling, Mark Thompson, Clark Valentine, Andrew White, Landon Winkler, and Linda Zayas-Palmer; Pathfinder GM Core © 2023 Paizo Inc., Designed by Logan Bonner and Mark Seifter. Authors: Amirali Attar Olyaee, Logan Bonner, Creighton Broadhurst, Jason Bulmahn, James Case, Jesse Decker, Eleanor Ferron, Fabby Garza Marroquín, Jaym Gates, Matthew Goetz, James Jacobs, Brian R. James, Jenny Jarzabski, Dustin Knight, Jason LeMaitre, Lyz Liddell, Luis Loza, Ron Lundeen, Stephen Radney-MacFarland, David N. Ross, Michael Sayre, Mark Seifter, Owen K.C. Stephens, Amber Stewart, Clark Valentine, Landon Winkler, and Linda Zayas-Palmer; Pathfinder Monster Core © 2024 Paizo Inc., Authors: Alexander Augunas, Dennis Baker, Kate Baker, Joshua Birdsong, Joseph Blomquist, Logan Bonner, Jason Bulmahn, James Case, John Compton, Paris Crenshaw, Adam Daigle, Darrin Drader, Brian Duckwitz, Robert N. Emerson, Scott Fernandez, Eleanor Ferron, Leo Glass, Matthew Goodall, BJ Hensley, Thurston Hillman, Vanessa Hoskins, James Jacobs, Jenny Jarzabski, Miko Kallio, Jason Keeley, Jeff Lee, Lyz Liddell, Luis Loza, Ron Lundeen, Robert G. McCreary, Philippe-Antoine Menard, Jacob W. Michaels, Dave Nelson, Jason Nelson, Tim Nightengale, Stephen Radney-MacFarland, Mikhail Rekun, Patrick Renie, Alex Riggs, David N. Ross, Michael Sayre, Mark Seifter, Chris S. Sims, Amber Stewart, Jeffrey Swank, William Thompson, Jason Tondro, Clark Valentine, Landon Winkler, Tonya Woldridge, and Linda Zayas-Palmer. If you use our Licensed Material in your own published work, please credit us as follows: Biomes, Pathfinder Second Edition rules layer © 2026 Michael Ghelfi. Reserved Material: the names of Biomes and its catalogues, its descriptions, sounds, art and code. Pathfinder is a registered trademark of Paizo Inc.; this site is not published, endorsed, or specifically approved by Paizo Inc.

Adventure hooks

  1. A herbalist has lived thirty years in the poisoned land in perfect health, and she sells a tonic she swears is the reason. The tonic is pond water: she is well because she has swallowed a little poison every day of her life, and now she wants to move to town to meet her grandchildren.
  2. A lord has heard that the poison yields the finest yellow dye in the kingdom and has sent his steward to fetch a barrel of it. The steward is terrified, unfailingly polite, and under orders not to come home with less than a full barrel.
  3. The poison spreads a mile further every year, and it has a source: for a century the alchemists of the nearest town have buried their failed brews here. Their new mistress did not know, and now that she does, she has decided it would be cheaper to make sure nobody else ever finds out.
  4. A boy from the edge of the poisoned land has tamed one of its creatures, small, bright and deadly to touch, and his father wants it killed. It has saved the boy’s life twice already, and the water it drinks from runs clear for a day afterwards.
  5. The miners have broken into a gallery nobody dug, its walls smoothed by tools, its floor worn by feet. The owner wants it explored before the men refuse to go back down.
  6. The owner has stopped paying, claiming the vein is worked out. The miners know it is not, and they know he walled up the richest galleries after the collapse, with two of their friends still behind the wall.
  7. A retired miner, nearly blind, wants to go down once more to the place where he first struck the vein. He will find the way only by the sound of the water, and he wants company, not help.
  8. The miners leave bread for the little folk of the mine so they will knock before a roof falls. The new foreman stopped the custom to save money, and now the knocking never stops, at any hour, everywhere.

Creatures

Also met here

This work includes material from the System Reference Document 5.2.1 ("SRD 5.2.1") by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2.1 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

To gather

Ooze Portion, Iron Vitriol

The same milieu, otherwise

Mine, Corrupted Mine, Haunted Mine, Crystalline Mine, Fungal Mine, Dead Mine, Eldritch Mine, Burning Mine

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