Menglis

On the inner planes, unlike the outer ones, a traveler can simply walk across from one plane into the next, the conditions shifting so gradually that he crosses the border before he notices. These strange margins produce an equally strange resident: the menglis, a spirit born of clashing opposites.

It is effectively invisible. Those able to see the unseen perceive a 10-foot humanoid shape, colorless and vague. It has no language but speaks through telepathy.

A menglis is neither aggressive nor a predator, yet its presence alone is lethal. Everything within 30 feet begins to separate into its basic elements. A living creature must save vs. petrification or start dissolving over 2d6 rounds, suffering 2d8 damage each round until the process ends. Only cure disease, heal, any hold spell or a suitable remove curse stops it, and damage already taken heals normally.

Each object in range must save vs. disintegration or break down in only 1d4 rounds; a spear's head might crumble into stone and minerals while its shaft releases a flash of positive energy and melts into water. Casting item, mend or remove curse before the object is gone halts and even undoes this. Leaving the area also stops both kinds of decay, and a creature or object that saves once is safe from that menglis for the rest of the day.

Killing the spirit ends all transformations, so it defends itself with a savage physical blow for 2d4+4. Mostly, though, it is incorporeal and hard to hurt: only +1 or better weapons affect it, and elemental magic and attacks of any kind fail. With great effort it can suppress its aura briefly, to converse for instance, but it rarely bothers.

Besides planar borders, a menglis may rarely dwell wherever one element intrudes on another, such as an air bubble deep within elemental Earth or a stray cloud of steam amid elemental Fire. None has ever been seen with another. Each lives alone, sustained by the shift from one element into the next, and is trapped there: forced out, or left behind when its border zone is altered or destroyed, it simply ceases to exist.

Menglis do not eat, reproduce or seek contact with anyone. Yet the growing menace of the chaos-eaters, which ravage the elemental borders the spirits depend on, may push them to reach out to others for help.