Crystalline Cave

Cave
Dave Bunnell / Under Earth Images, CC BY-SA 2.5, 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. Hollows in the rock, from a shelter under a ledge to networks that run for kilometres. Dark, cool and the same temperature all year, home to bats and pale creatures, and to whatever people bring or hide there.

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.
  • Getting lost. Under the trees, in the dunes or in the dark, every direction looks alike. Without a guide or a sure landmark, a party walks in circles.
  • 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.
  • 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 30 · Sense Direction: Survival DC 20
  • Getting lost. Sense Direction (Player Core p. 246): a Survival check once a day, –2 without a compass; DC 15 in ordinary wild land, 20 in deep forest or underground, 30 in a featureless desert. Getting lost has no fixed penalty: the GM decides where the party ends up.
  • 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.

A scene

  • Simple Cave. The cave murmurs and sighs. A slow, cycling breath that carries no warmth and no explanation. Deeper within, water chooses to occasionally drip. The dark is total beyond the reach of any flame. Somewhere above, or perhaps below, something shifts in the stone. This cave is not empty. It is never empty. And it is never full. The full generator on the blog

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. A shepherd’s dog chased a fox into a crack in the hillside and came back carrying the jaw of a cave bear. The shepherd wants the crack walled up; his son wants to see the rest of the bear.
  6. The bats have stopped leaving their cave at dusk. The guano diggers who sell the droppings to farmers are out of work, and something deep in the cave is keeping the bats in.
  7. Animals painted thousands of years ago cover the walls of a deep chamber. An old woman who lives at the cave mouth adds a new one every spring, in the same hand, and will not say who taught her.
  8. The town ages its cheeses in a cool cave, and the cheeses have started to disappear. Whoever takes them leaves coins in exchange, fair payment, minted by a king nobody has heard of.

Animals

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

Amethyst Dragon Tonsils, Bat Guano, Brutacian Lung, Bugbear Tooth, Deep Gnome Nose, Fire Beetle Glands, Obsidian Powder, Ooze Portion, Scorpion Venom, Sulfur Pinch, Topaz Powder, Tourmaline Powder, Troglodyte Thumb Nail, Amber Tears, Amethyst Powder, Aquamarine Powder, Black Powder, Bloodstone Powder, Chalcedony Powder, Chitine Silk, Cockatrice Liver, Crystal Powder, Echo in Stone, Ettercap Mandible, Ettin Toe, Firenewt Bile, Fixed Nitre, Galeb Duhr Soul, Giant Spider Perfect Eye, Jade Powder, Jasper Powder, Jet Powder, Lapis Lazuli Powder, Magnetite Shavings, Malachite Powder, Moonstone Powder, Myconid Spores, Phase Beast Heart, Ruby Powder, Sapphire Powder, Selenite Sliver, Native Sulfur Crystal, Tanzanite Powder, Young Dragon Tonsils, Zircon Powder, Ankheg Antennae, Basilisk Throat, Cyclops Eye, Drider Tongue, Flumph Hypothalamus, Grell Beak, Minotaur Heart, Ogre Liver, Phase Spider Egg, Troll Bone Marrow, Dragon Tonsils, Gorgon Muzzle, Roper Bile, Shadow Mastodont Eye, Adamantine Dragon Tonsils, Iridium Powder, Purple Worm Bile, Sapphire Dragon Tonsils, Shadow Dragon Gland, Topaz Dragon Tonsils, Tungsten Powder, Wyvern Poison

The same milieu, otherwise

Cave, Cursed Cave, Blessed Cave, Corrupted Cave, Haunted Cave, Fungal Cave, Enchanted Cave, Primeval Cave, Eldritch Cave, Frozen Cave, Toxic Cave, Burning Cave

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