Crystalmist

A crystalmist was a hive-like swarm of crystalline creatures that consumed sunlight.

Description
An individual crystalmist closely resembled a snowflake, at the core of which was a point of light that pulsated and slowly changed color over the course of the day. However, their most recognizable form, the one that a swarm adopted when they felt threatened, was a sphere around wide. This sphere shimmered with white light and emitted a deep throbbing sound, one described as ominous.

Behavior
Individual crystalmists had no intelligence to speak of—they were estimated to be less intelligent than the typical grasshopper. They simply drifted on the breeze as they absorbed sunlight. Nevertheless, they had the basic instinct to stay close to one another and to form a defensive sphere and even swarms of several hundred specimens, though with no noticeable social organization. In a sphere, their intelligence rose slightly, comparable to a non-insect animal. They were thought to communicate in a basic manner by modulating their colors.

Combat
When a swarm felt threatened for some reason, individual crystalmists moved into their defensive sphere, comprising about fifty members. While individuals had no means of attack or defense apart from their tiny size, and were easily destroyed, this community was much more potent and capable, but slower. Formation took only a minute.

If the sphere was damaged, individual crystalmists were destroyed, and losing ten or more of them caused the sphere to break apart into individuals once more. These could not reform for at least five minutes.

Abilities
When in a sphere, the individual crystalmists could all release their stored energy at once, producing an intense beam of light capable of burning creatures it struck, up to a distance of, after which it was too diffuse. Sometimes, the beam could reflect off a metallic surface such as a shield or armor, and strike something else in the area. The light was strong enough to ignite flammable materials such as clothing, padded armor, wooden shields, and so on, and explode combustibles like lanterns, thus causing injury and destruction beyond the initial beam. A bright light source in the vicinity, like a continual light, doubled the beam's intensity. The crystalmists could emit a beam approximately once a minute.

Crystalmists were of course immune to mind-altering spells like sleep and charm and to illusions.

Ecology
Crystalmists absorbed light, usually sunlight, to provide energy for their crystalline structures. They did not prey on any other creature, and other creatures did not as a rule prey on them, though flying creatures like birds and bats occasionally scooped them out of the air in order to balance their diets with additional minerals. By and large, animals paid them no attention.

On rare occasions, an individual crystalmist procreated via binary fission, that is, by splitting into two.

Lands
Crystalmists were normally found on the world of Oerth.

However, on Toril, a crystalmist swarm lived in the choraula of the House of the Moon temple to Selûne in Waterdeep circa 1370 DR. They fed on the light provided by the continual light spells there. A very old spell stopped them from both leaving the room and adopting their defense formation. Only a moderately experienced Selûnite priest could make them coalesce and attack others.

Uses
The crystalmists' unique physiology meant they were very valuable in the making of magical items. At the most basic, crystalmists could be used to make dust of illusion and even smoke powder to a high quality. Furthermore, it was theorized that ground crystalmists went into the making of the timeglass of the mage known on Oerth, and that captive crystalmist colonies were trapped forever inside the unique crystal balls known as the oracles of Greyhawk, and would be there forever.