Crazed Spirit

Incorporeal Movement. The spirit can move through other creatures and objects as if they were difficult terrain. It takes  1d10 force damage if it ends its turn inside an object.

Impenetrable Frame. The crazed spirit has a strong soul, the only way to vanquish it is to land a critical hit.

Magic Protection Field. The crazed spirit has gained a magic field that allows it to pass spell DC's of 15 or lower that causes it harm automatically and will take no damage if the spell deals damage on a successful save. (Ex. Fireball, Viscous Mockery, Lighting Bolt, etc.)

Withering Touch. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Damage 4d6 necrotic damage

Strength Sap. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Damage (2d6+5) necrotic damage, and the targets’s Strength score is reduced by 1d6. The target dies if the target’s Strength score is reduced to 0. This lasts until a long rest is taken. If a non-evil humanoid dies form the attack a specter/poltergeist rises from the corpse in 1d6 hours. If the humanoid has an evil alignment a crazed spirit will rise in 1d6 hours.

Chill. Ranged Spell Attack. +4 to hit. Range 15 ft., one target. Damage (2d4+enemies constitution modifier) cold damage.