A New Vessel

You need a body. Without one, you're trapped wherever your vessel may be. You soon discover that, from your prison, you're able to exert your will on a passerby. By happenstance, a local hunter prowling through the forest, or perhaps a lone adventurer braving the frozen tundras, wanders nearby. No matter the case, any body would be preferable to an eternity of inanimacy.

Soulbound Traits

As a bound spirit, your physical form is restricted to the vessel you are bound to. Your soul, however, has its own set of traits to help you survive in the Material Plane.

Soulbound. Your soul is bound to an unusual phylactery called a Soulstone. You know the location of the Soulstone at all times if it is within 100 feet of you. While your soul inhabits the Soulstone, you can't move or use reactions, but you are aware of your surroundings as if you were in the Soulstone's space. The only action you can take is to project your soul in an attempt to possess a humanoid.

Possession. As an action, you can attempt to possess a humanoid you can see within 100 feet of the Soulstone. Creatures warded by Protection from Evil and Good or Magic Circle are unaffected. The target must make a Charisma saving throw against your spellcasting DC. On a failure, you assume control of the target's body, and the target's soul becomes dormant. On a success, the target resists your efforts to possess it, and you can't attempt to possess it again for 24 hours.

Assimilation. Once you possess a creature's body, you control it indefinitely. You retain your game statistics and alignment. If the host body’s Strength, Dexterity, and Constitution scores differ from your own, the body rapidly changes to reflect your ability scores over the course of one week. You retain the benefit of your own class features. If the target has any class levels, you can't use any of its class features.

Ending Possession. While possessing a creature, you can use your action to return from the host body to your Soulstone if it is within 100 feet of you, allowing the host’s soul to regain control of its body. If the host body fails three death saving throws while possessed, the host dies and you must make a Charisma saving throw against your own spellcasting DC. On a success, you return to the Soulstone if it is within 100 feet of you. Otherwise, you die. If the Soulstone is out of range or destroyed when possession ends, you die.

Soulstone Destruction. If the Soulstone is destroyed while your soul is possessing a creature, your soul remains in the host’s body. If the Soulstone is destroyed while your soul inhabits it, you die.

Racial Traits. You assume the Age, Appearance, Senses, Size, and Speed of your host.

Cling to Life. When you make a death saving throw and roll 16 or higher, you regain 1 hit point.

Revenance. You retain the creature type of your host, yet you register as undead to spells and other effects that detect the presence of the undead creature type.

Unsettling Presence. As an action, you can unsettle a creature you can see within 15 feet of you. The target has disadvantage on the next saving throw it makes within the next minute. Constructs, undead, and creatures that can't be frightened are immune to this feature. Once you use this feature, you can't use it again until you finish a long rest.