Exorcism

The caster attempts to force a ghost, demon, or other such entity to leave its possessed host. The creature possessed by the entity must either be willing or restrained for this spell to function.

After an hour of reciting liturgy, chanting, waving burning sage around, carving magic sigils into the creature's skin, etc., the entity must make a saving throw using either Charisma, Constitution, or Wisdom. On a failure, it takes 2d10 psychic damage and its hit point total is reduced by that amount. It must then make a second saving throw, using the same ability as above. Should that fail, it also loses a number of points from the given attribute equal to the caster's spellcasting modifier.

If the entity fails its first saving throw, the caster must make a Constitution saving throw. On a failure, they and the host creature take 1d10 psychic damage.

One casting of this spell will generally only weaken the spirit; it often requires multiple castings to fully drive it off. Once the entity's max health is reduced to 1, or any of its modifiers reach 3 or less, then it loses the ability to retain hold on the host and is cast out. The host is immune to possession for one year thereafter, until the magic sigils carved into them begin to fail.

At Higher Levels: When this spell is cast using a spell slot of 2nd level or higher, all damage is increased by 1d10 per slot level.