Crystalline Mine

Mine
Partonez, CC BY-SA 4.0, Wikimedia Commons

Crystals grow out of the ground, the rocks and even the plants. They cut, they ring in the wind, and they throw light in every direction, so that noon dazzles and the night glows. 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.
  • Crystal shards. Crystal edges hide under grass and sand, sharp as glass. Boots last a week; bare feet, an hour.
  • Singing stone. When the wind blows the crystals ring, one long note that never stops. After a day of it, nobody hears anything else, and some stop sleeping.
  • Crystal glare. At midday the light bounces from every face of the crystals. Without a veil or slitted goggles, the eyes burn.

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.
  • Crystal shards. (House rule) The ground is Difficult Terrain. A creature that moves at a fast pace makes a DC 12 Dexterity save each hour or takes 1d6 slashing damage and has its speed reduced by 10 feet until healed.
  • Singing stone. (House rule) On windy days, creatures have Disadvantage on Wisdom (Perception) checks that rely on hearing. A creature that sleeps without stopping its ears makes a DC 12 Constitution save or gains 1 Exhaustion.
  • Crystal glare. (House rule) A creature that travels at midday without eye cover makes a DC 12 Constitution save or has the Blinded condition until it rests an hour in shade.

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 jeweller pays well for crystals cut from living plants, which hold a little green inside. The plants scream when they are cut, a thin ringing scream, and the jeweller has stopped coming himself.
  2. The crystals ring in the wind, and someone has noticed that, played together, they make a song the oldest grandmother in the region knows. She will not sing the end of it.
  3. The crystals are spreading a little further each year, onto farmland, roofs and once onto a sleeping drunk. The village wants it stopped, and the drunk would like his arm back.
  4. A thief has stolen a sack of the crystals and hidden in the land, and every crystal he carries shines a light that can be seen for miles. He is the worst hidden man alive, and the most heavily armed.
  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.

The same milieu, otherwise

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

Open it in Biomes — MGS Toolbox