Kuei

In appearance a kuei is unchanged from the moment it died, the same age and in the same clothes. It seems solid, yet anything passes harmlessly through it. It speaks the languages it knew in life in a flat, toneless drone.

A kuei's powers scale with its Hit Dice: about 10% have 3 HD, 20% have 4, 40% have 5 and 20% have 6, though the DM may tailor this to the person it once was, a mighty hero returning with 6 HD and a weakling with 3.

Any kuei can go ethereal at will and possess a host three times per day. ESP, charm, enchantment, illusion and water-based spells all fail against it. Normal fire and cold cannot hurt it, and magical fire or cold does half damage.

It usually tries first to possess the healthiest, most dangerous-looking foe. If it succeeds its own form vanishes, and it drives the body toward whatever unfinished task holds it on the Prime Material Plane, using its own powers rather than the host's. The possession ends only if the host dies, the task is finished, or an exorcism or similar spirit-banishing spell expels it; the host then recovers with no memory of the episode.

Its alignment matches its purpose, such as avenging its murder, keeping an oath, or arranging the temple rites that would free it. Bound by an oath, it may stay in a host indefinitely: one sworn to marry might live in a bride's body beside her husband for years if he never notices.

Kuei roam without lairs or treasure, usually within a few miles of where they died but potentially anywhere from arctic ice to desert. Sunlight does not harm them, yet they are most active by night.

Kuei neither eat nor sleep; their daytime idleness is closer to meditation. A possessing kuei fakes both to avoid discovery. They avoid other creatures, though evil schemers sometimes steer them toward victims.