Unbound Spirit Traits

  Braythebound. Unbound Spirits cannot be permanently destroyed. If they are killed, they reform with full health in the vicinity of their point of death at the next dusk.   Nocturnal Existence. Unbound Spirits appear at dusk and disappear at dawn.   Semi-corporeal Existence. Unbound Spirits are, most of the time, semi-corporeal. In this state, they gain the abilities Incorporeal Movement and Incorporeal Immunities. Attacks made by the spirit in this state only inflict necrotic damage, but no physical damage (except against other semi- or incorporeal creatures).
As a bonus action, the spirit can decide to become corporeal. It then loses the abilities Incorporeal Movement and Incorporeal Immunities, but its attacks become physical and now inflict all damage types.   Incorporeal Movement. In semi-corporeal state, the Unbound Spirit can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.   Incorporeal Immunities. In semi-corporeal state, the Unbound Spirit is immune to piercing, slashing and bludgeoning damage by non-magical weapons.   Undead Immunities. Unbound Spirits have the following condition immunities: Blinded, charmed, exhaustion, frightened, paralyzed, petrified, poisoned.
They are also immune to the following damage types: Cold, necrotic, poison.   Object Possession (Recharge 6). When succeeding on a Wisdom check against DC 13, the spirit can possess an object with no more hit points than the Unbound Spirit. The spirit disappears, and gains control of the object. The effect is similar as if the Unbound Spirit had cast Animate Objects, but affects a single item with an unlimited duration, and has a range of 5 feet. When possessing an object, the Unbound Spirit doesn’t disappear at dawn (unless it chooses to do so, upon which the possession ends). The spirit can't be targeted by any attack, spell, or other effect, except ones that turn Undead, and it retains its Alignment, Intelligence, Wisdom, Charisma, and immunity to being Charmed and Frightened. It otherwise uses the possessed target's statistics.   The possession lasts until the object drops to 0 Hit Points, the spirit ends it as a Bonus Action, or the spirit is turned or forced out by an Effect like the Dispel Evil and Good spell. When the possession ends, the spirit reappears in an unoccupied space within 5 ft. of the body. The target object is immune to this spirit’s Possession for 24 hours after a possession attempt fails or the possession ends.   Creature Possession (Recharge 6). One creature that the spirit can see within 5 ft. of it must succeed on a DC 13 Charisma saving throw or be possessed by the spirit; the Unbound Spirit then disappears, and the target is Incapacitated and loses control of its body and falls into a state of unconsciousness. The spirit now controls the body. The spirit can't be targeted by any Attack, spell, or other Effect, except ones that turn Undead, and it retains its Alignment, Intelligence, Wisdom, Charisma, and immunity to being Charmed and Frightened. It otherwise uses the possessed target's Statistics, but doesn't gain access to the target's knowledge, Class Features, or Proficiencies.   If the target is willing, it can omit the Saving Throw, and in return stays fully conscious. The Unbound Spirit can even decide to give back control of the body temporarily without ending the possession.   The possession lasts until the body drops to 0 Hit Points, the spirit ends it as a Bonus Action, or the spirit is turned or forced out by an Effect like the Dispel Evil and Good spell. When the possession ends, the spirit reappears in an unoccupied space within 5 ft. of the body. The target is immune to this spirit’s Possession for 24 hours after succeeding on the saving throw or after the possession ends.  

Other Traits

  Magic Resistance. The Unbound Vengeance Demon has advantage on saving throws against spells and other magical effects.