Ephemeral

Ephemerals are bodiless undead, thought to be the spirits of people who perished in the flame-sea that fills the gulf between crystal shells. They look like gray, dusty human figures. Their forms are believed to be bound to the Negative Material plane while also soaked through with the substance of the flame-sea, which makes them vulnerable to fire but lets them knit themselves back together. Magical energy draws them, so a passing starhelm may attract a pack.

An ephemeral's touch deals 1-4 points of damage and drains 1-2 points of Intelligence. A sentient humanoid killed by that damage rises as a new ephemeral in 2-8 days. One whose Intelligence is drained to nothing becomes a host for the spirit instead, as described below.

Only magical weapons affect them in melee. Like other undead they ignore sleep, charm and hold spells and cold attacks. Fire always does maximum damage to them, though using fire in the flame-sea is a dangerous gamble. By drawing the surrounding medium into themselves they regenerate 1 hit point per round, unless somehow cut off from it. At 0 hit points an ephemeral dissipates forever.

Clerics in the flame-sea usually cannot reach their deities, so ephemerals generally cannot be turned. A priest who does keep contact with his or her power may try, and turns them as spectres.

They attack as a pack whenever possible, seeking to empty the minds of as many humanoids as possible and claim them as bodies, while the rest are killed and thrown over the side. Badly hurt, they fall back and trail the ship, striking again once they have healed.

Packs drift through the flame-sea, made of the dead or the cursed who died there. Barred from their homes and from whatever reward or punishment awaits in the afterlife, they become spiteful, petty spirits with one purpose: to reach a final resting place at last.

Living bodies are their way back. An ephemeral drains a single character's mind to gain passage to a safe crystal shell. Without a living body under its control it cannot pass through a shell, and if forced through it is teleported at random deeper into the flame-sea.

No one knows where ephemerals came from. Perhaps they are the remnants of a people who cracked their own crystal shell and let the flame-sea pour in. Whatever their origin, they have multiplied by preying on thinking beings crossing between shells, and humans, mind reavers and web-eel slavers have all fought them in transit.

A possessed body keeps its own physical traits. If ordinary weapons could harm it before, they still can, and it gains neither the spirit's weakness to fire nor its ability to regenerate. A slain host is useless to the ephemeral. Any magic that defeats magic jar also ends this possession.

Once inside a host, the ephemeral sets out at once for a crystal shell, often killing anyone who stands in its way, former allies included. It can use the body's physical abilities but none of its magical or special powers; a possessed mind reaver, for instance, would be unable to unleash its mental blast. The moment the host crosses into a shell, the spirit flees it, leaving a living but empty body with 0 Intelligence. Only a full wish restores the mind, and until then other bodiless spirits may move in unless the body is warded by protection from evil (or good) or similar magic.