Soulmist
From Mizahar Lore
Soulmist is the substance that composed a ghost's Soul, specifically replacing their Astral Body. A ghost, no matter how they appeared, is always composed of Soulmist. Their skin, clothes, hair, and other parts, those are merely different appearances, all composed by Soulmist. Soulmist is ethereal and can pass through physical objects. Shredding a ghost's soulmist hurts the ghost, too much damage to its soulmist will cause a ghost to be incapacitated as they slowly recover.
A ghost uses its soulmist for various purposes, mainly materializing, interacting with the world, or possessing a host.
A branch of world magic, called Spiritism, enables the user to exhume the substance, a spiritist can use his soulmist for various purposes, feeding a ghost, enchanting weapons and armor, or creating ghost-hunting equipments.