Flareater

A flareater was a rare, fast-moving, and intelligent ooze that searched for sources of light. "Those who witness flareaters say their movement is unnerving, like watching dark, evil water flowing over stone walls."

- Excerpt from The Ruins of Undermountain II: The Deep Levels

Description
Flareaters seemed to be related to green slimes, perhaps experimentally modified via the use of magic. As such, their bodies were very warm. They had long dark green bodies, which appeared glossy in the light. In their typical environment of dark, subterranean passages, they appeared almost black.

Behavior
Unlike almost all other oozes, flareaters were intelligent. In fact, they were far more intelligent than animals, and paralleled the intellect of humans. As well as their surprisingly high intelligence, flareaters could move very quickly. They were described to be able to move like running water to overtake their foes.

It was unknown how these intelligent creature communicated with one another. However, it was believed that they could commune via pulsating ripples.

Flareaters constantly sought out their favourite source of food: light.

Combat
Before entering combat, these intelligent creatures stalked their foes. When doing so, they assessed the strengths and weaknesses of their potential targets, and used this information to decide who to attack first. When a target was chosen, flareaters would find the best method to surprise them, which was usually by dropping on them from ceilings. If the target was carrying a light source, the flareaters would drop into that instead, extinguishing the flame and gaining health.

When in contact with their victims, flareaters started to dissolve their flesh, as well as both wood, leather, metal, and magical equipment. Unlike other oozes, flareaters were notoriously hard to scrape off the material they were dissolving, as they would try to dissolve the scraping tool itself.

Such oozes were resistant to sources of heat and fire, as well as all spells associated with them, such as fireball and Melf's minute meteors. Light-based spells, such as moonbeam and dancing lights, would actually cause the creature to expand and become even more powerful. If multiple of these spells were cast on it, flareaters would become even larger, and split off into two separate flareaters.

Society
Flareaters could either be found alone, or in groups of up to four. It was rumored that huge colonies of such creatures were found in the lowest levels of Undermountain.

Uses
These powerful oozes were sometimes sought out by wizards. As flareaters were immune to sources of heat and fire, they could be used in potions that mimicked these effects. Part of their bodies could also be used in potent spells such as shapechange or create darkness.

History
The archmage, Spite Harrowdale, kept a flareater in his Undermountain abode. It was kept in a room with an extremely heavy stone door, as otherwise it would wreak havoc.