Chaos beast

A chaos beast was a horrible and ever-changing creature of the planes. Its lethal touch could transform a victim into an amorphous mass, and ultimately a chaos beast themselves.

Description
A chaos beast had no fixed, original, or true form whatsoever. Instead, it was entirely mutable and always changing, melting, and reshaping itself into new and nightmarish forms. There was no way to predict it and it might try a dozen before adopting one for a time. Some recorded appearances were:
 * A towering thing of pulpy flesh and exposed veins, covered in fangs and hooks. It had three legs upon which it walked with unsteady and lurching steps. Its face was fractured, with bent eyes and nose hooked three times. Agonized by this shape, it roared with pain and rage.
 * A filmy mass of rope-like tentacles with vermilion tips that slithered along. It had a bulbous body ringed by gnashing mouths and topped by a viscous sac holding ten bobbing eyes. It had dozens of vestigial wings that flapped too feebly to give it flight.
 * A powerful and muscular beast, armed with claws and alligator jaws. It charged and attacked furiously.
 * A graceful six-legged creature with delicate arms and shining skin. It had a maned head with three flashing eyes. It walked with a smooth gait and noble bearing.
 * A man-sized creature with stumpy feet it could only shuffle on and hands like crab's claws. Its body was like dough falling from broken bones. Its head was balding and pitted with empty eye sockets. It whimpered pathetically.

It could be any or all of these, or something else entirely. While its height, length, and breadth might change, a chaos beast generally had a mass of around and a height of between  and. However, they could grow much larger, and more powerful.
 * A slender raptor-like creature with large talons underneath its body and broad wings, all covered with dark fur. It had two hateful coldly gleaming eyes and moved quickly and quietly except to shrill when it attacked.
 * A sac of intestines, warm and wet and steaming and both deaf and blind. To move, it rolled and flopped like limp sausages falling down stairs, becoming looped and draped around all obstacles and lying as a tangled sprawl.
 * A hollowed-out carcass, swelling with gases into a balloon-like husk, bobbing along with the ends of its body trailing about it and tangling others.
 * A plump moth with brilliantly colored wings like the stained glass of temples and compound eyes that sparkled like a myriad of jewels.
 * The person one least suspected.

Combat
A chaos beast attacked with whatever suitable body part it had at the time, such as claws or pincers, tentacles, fangs, or spines. However, as disturbing and adaptable as this might be, it was not physically very dangerous, being relatively weak and unable to fight with more than two at a time, as its constant changes meant it lacked sufficient coordination, or else it wasn't smart enough to make best use of its shapes. Its blows were feeble, whatever size or shape the attacking appendage took. However, its strike alone was chaotic and deadly.

Abilities
Whatever its body part, the touch of a chaos beast against the bare flesh of a living creature inflicted a hideous transformation. Those who could not resist through physical fortitude suffered a corporeal instability, turning their body soft and spongy and gradually losing all sense of form, and melting, flowing, writhing, and bubbling until reduced to an amorphous mass. This was incredibly debilitating: feet and legs became misshapen and weak, slowing their speed; their hands could no longer grip onto things; all worn items became useless and even restrictive as the body bulged, hindering agility. The twisted nerves caused agonizing pain, preventing the victim acting sensibly: unable to recognize allies and enemies, they attacked blindly and clumsily, and they were incapable of using magic. Furthermore, the shock and trauma deteriorated their sanity, increasingly and permanently, until they managed to regain control over their body.

With effort and confidence, as if their own body was a part of Limbo that they must control, a victim could halt and control the transformation and reassume their original form, and keep trying until they did, but only for a minute. It took constant effort and maintenance to keep their own treacherous body from becoming unstable again; another person could apply the force of will needed to give the victim some time to rest. This corporeal instability was neither a curse nor a disease, but something else, and hence it was difficult to get rid of. Their form could be fixed by compulsive order, shapechange, and stoneskin spells, with no other effects, but only for their duration. Spells like heal, restoration, greater restoration, stabilize, or even limited wish were needed to lift the instability and restore the body, but not necessarily their sanity.

A victim who could not regain control was left a mindless and bodiless monstrosity, even a shapeless goo. Moreover, it was widely believed that those who did but remained afflicted went on until their madness and body horror became all consuming and they ultimately became chaos beasts themselves. This was, unfortunately, true.

Forever changing its form, no magic made by mortals could trap a chaos beast in a single form or force it into another. A polymorph spell or even petrification effects forced a chaos beast into a new shape, but several seconds later, it could turn back or take another at ease. It was resistant to spells in general, and its inconsistent anatomy made it hard to seriously injure.

Origins
Chaos beasts were found in the Ever-Changing Chaos of Limbo, along the River Styx, at the Supreme Throne of Cyric, and in the wilderness of Set's realm of Ankhwugaht in Heliopolis.

Chaos beasts were native to Limbo. Material plane-dwellers unfamiliar with Limbo mistakenly believed them to be a kind of chaos elemental.

Personality
Though they might have many mouths, they did not say anything.

Activities
Changing incessantly, a chaos beast's breeding habits and behaviors seemed pointless to even guess at. Those of Limbo consumed the "chaos-stuff" of that plane, while one was known to consume the bones of its prey.

They wandered randomly and did not defend any territory, though they avoided the stabilized, ordered parts of Limbo, tending to be found in the more chaotic parts. Chaos beasts were always encountered alone, mercifully.

Uses
A chaos beast could be summoned with the summon monster VI spell. For example, a trap in the Tomb of Vorbyx in the Thar would summon a chaos beast if triggered.

Once slain or severed from the body, the flesh of a chaos beast was a protoplasm-like substance, but it lost all its potency in moments. Although wizards researched a way to use it as a powerful component in shapechange potions, no known use for it was recorded.

Significance
Chaos beasts were favored monsters of the elven god Erevan Ilesere, who was called the Ever-shifting Shapechanger. They were known to serve him.

History
A huge chaos beast once attacked the halfling settlement of Barnstable in Limbo.

Chaos beasts and cloakers were noted to emerge from the caverns of Taerymdoom beneath the southeastern Far Forest in the Savage Frontier by 1372 DR.

A chaos beast was kept as a servant by the lizardfolk band led by lizard king Kha'ghassta. At the ruined temple of the World Serpent they occupied around 1373 DR, the chaos beast made its lair in the old library, and it was allowed out to hunt humanoids and animals in the area.

Chaos beasts might be encountered in the River Graymurk in the Maze Level of Undermountain around 1375 DR.

Notable Chaos Beasts

 * The Xaos, a chaos beast of twice the normal size in service to Telkoun Adranther at Telkoun's Tower around 1372 DR.
 * The Brethren, a score of chaos beasts in the Forbidden Chambers of Aldinach's Egg in the Abyss, to whom guests who outstayed their welcome were fed.