He was thrown roughly against one of the crystals, and then lashed against it. He could see the high priest - Father Crinbon, though he certainly doubted that was his real name. Fath- whoever his name was, knew too much about him. The priest knew that he has been cast out by his family, that he had stolen - and worse. And that no-one would miss him.

The priest did not waste words on him. After checking that the ropes were properly restraining him, he pushed his victim's head up against the crystal, and spoke a word of command. A heartbeat later, the priest brought up his hammer and dashed it against the victim's forehead. One of the priests assistants quickly cut the ropes and the lifeless body dropped. A shadowy figure now appeared within the crystal and the priest smiled.

The Cavern, perhaps a hundred feet at its highest, is full of huge blood-red crystals emerging from floor, wall and ceiling, giving the impression of massive demonic fangs. Light sources are reflected and multiplied by the massive crystals, giving both brilliance and ghastliness to the place. Careful examination shows some of the crystals have shadowy silhouettes within, or small eye-like points of light.


The cave was natural in origin, well before the Clathrate nearby infused the crystals with infernal energy. The energy was what drew the first humans here - a sorcerous cult eager to make use of the Clathrate's power. They did not locate the Clathrate itself, as they found the crystals quite enough for their purposes.

The Crystals were used both as a power source, and as time went by, containers for a menagerie of demonic and mortal spirits. These were held to pump for information, demand favours, and sometimes in the case of their mortal victims, to deny them their afterlife. Suitably evil mortals had their spirits bartered with various dark powers.


The crystals bear enchantments to keep the spirits bound within them, and additional spells to keep the spirits from making too much noise or to lash out with magical abilities. These spells are generally in good shape, but the effects of the Clathrate promotes chaos, and some spells have weakened to the point that the cave frequently erupts into a cacophony of screams, threats, insults and other obscenities.

Some stones are hazardous to stand nearby, as some demons may be able to attempt to possess bystanders and possibly substitute their victim within. Others may be unable to escape, but will seek to draw other spirits into their prison for ‘entertainment'.


The Grand Crystal

Flanked by swarms of lesser, though empty crystals, a huge crystal sits in one corner of the cave. It is home to the cult's crowning achievement, a greater demonic power. This demon is livid at his imprisonment and has drawn into, and devoured, all of the spirits entombed nearby. If freed, the dark spirit within will shatter all nearby crystals and draw the shattered parts together to form a massive body to attack anyone else nearby. Once alone, he will seek to devour all of the other trapped beings, and then either depart back to Hell or leave the cave to wreck havoc on the world. GMs of course may use any greater demon native to their campaign.

The Pit:

The capturing of spirits left many corpses, and these were disposed of in a deep pit some distance from the cave. Of course, the Clathrate exerted its baleful effects on the corpses as well, and the pit now contains a number of undead abominations.

While they are currently in the pit, and mostly inactive, any battle in the crystal chamber is likely to rouse them from their stupor, and they will join the in the fun after a short interval. They hold no love for intruder, cultist, sorcerer or demon and will happily flay and devour anyone.

Smashed Crystal Effect/Crystal Contents

Die Roll





Mortal spirit, Ecstatic at freedom. Flees shouting for joy.


Weak insane Mortal spirit, invisible. Stays and flits about howling obscenities. Cannot otherwise interact and eventually drifts off.


Strong insane mortal spirit. Appears as white ghost. Uses fear-based attacks.


Strong insane mortal spirit. Invisible but capable of telekinetic attacks


Minor Demon


Major Demon

Insane spirits will strike out at anyone, or do other odd things, such as deliberately shattering other crystals, potentially causing a chain reaction.

Demons freed will follow their own bent, and judge the situation when freed. Their perception of time is such that they will not have been driven mad by their incarceration, and they choose to act against PC's, cultists, other demons or freed spirits.

Campaign Use

The cave is a location, and as such an element to be used in your own adventures. The existence of both undead and demonic threats makes it very suitable for high level adventures. As it is little more than a pair of caverns, it could be inserted into just about any dungeon.

Forgotten Spirits

In this case, the location is placed in the PC's path during some other underground incursion, perhaps behind a rockfall in a dungeon. It serves as a massive boobytrap in this case.

The location has been lost in years past - a catastrophic rockfall cut off access to the chamber, condemning all within to a slow death and leaving the spirits hidden and trapped. In such a case, it is likely all of the mortal spirits entrapped have gone mad. Potentially, cultists may have intentionally trapped themselves in the crystals rather than experience slow death by starvation.

Many spells have failed, and the spirits are only tenuously held within their prisons. The PC's intrusion would be just enough to rouse the spirits into sudden, mad pandemonium. Perhaps they sit quiet until one of the PC's does something stupid or noisy - or - intentionally damages or attempts to steal one of the massive ‘treasures'.

The Rescue

Someone important to the PCs has disappeared, or clues for a long missing person have arisen. They have been trapped in the crystal, and their bodies are gone. The PCs could either free the spirit to go to its just reward - a bitter victory if it can be called one - or perhaps some means could be found to gain a new shell. Of course, just getting here would be difficult, and locating which crystal contained their subject could lead to some seriously dangerous trial and error.

Reality Check

The crystals in this submission are much harder, and the wrong colour from those in the real location that inspired this submission.

See http://news.nationalgeographic.com/news/2010/09/photogalleries/101008-giant-crystal-cave-science-mexico-pictures/#/return-crystal-caves-16_27278_600x450.jpg

Gypsum Crystals, or Selenite, are quite soft and dull and apparently the cave is likely to be short lived.

Large, clear and hard crystals would be considered gemstones and having a cave full of man-sized rubies would do a serious number on your campaign, at least with regards to the value of such gemstones.

Next Steps:

A much better table containing demonic and mortal spirits. Suggestions welcome!

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