Path of the Possessed

For some barbarians the rage inside them comes from emotional trauma, for some its the wrath of nature itself. But for some the monster inside them is more literal than figurative. If a being from the lower plains possesses someone with a powerful enough will to suppress that entity... then that entity could be used as a power source. Bringing the Fury of a demon, the power of the Hells into your body and using it as a weapon, that is the path of the possessed. 

Although the basis is the same for all those with this path thrust apon them, the specifics of the entity inside them will bring about different changes, and this beings willingness to cooperate with its host will also vary wildly. did you make a pact with this entity, or did it invade your body, or even... did you capture it? 

Feindish Possession

The Fiend inside you makes you more like itself when you rage, when you are raging you gain resistance to necrotic and fire damage, and you gain advantage on Intimitate checks. In addition when you rage you count as a fiend in addition to your other creature types.

Fiendish Blessing

At 3rd level when you acquire this path, the fiend inside you manifests itself when you rage. You may choose one of the following options to determine how it empowers or transforms your body when raging.

Demonic Claws

While you're raging your hands transform into shadowy demon claws. These claws are treated as natural weapons that you are proficient with. these claws deal 1d6+STR slashing damage and count as magical weapons. when you use your action to make an unarmed attack or natural weapon attack you may use your bonus action to make one unarmed attack with your demonic claws.

Hellish Fury

While you're raging you channel the power of the Hells into your weapon attacks. The first creature you hit on each of your turns with a weapon attack takes additional fire damage equel to 1d6+half your barbarian level.

Feed the Beast

At 6th level the fiend inside you can feed on the death and chaos of battle sustaining itself and you. you gain one of the following traits

Essence Devour

When a creature dies within 10 feet of you, you may use your reaction to have the fiend inside of you feed on what is left of its essence. when you do so you gain temporary hit points equal to your Con mod(minimum of +1)+ half your barbarian level.

Thirsting Fangs

When you rage your mouth shifts and elongates. Your teeth become needle like fangs, you gain a bite attack that deals 1d8+Str piercing damage. you are proficient with this attack. you may only make one bite attack per turn. when you hit a creature with your bite attack you may deal an additional Necrotic damage equal to your Constitution Modifier. when you do so you heal an amount equal to the necrotic damage you deal. You may only heal this way when you are at half hit points or less. 

Fiendish Essence

At 10th level you gain additional benefits from the Fiend inside you. You gain dark vision for 60ft and magical darkness does not impede your dark vision. in addition you gain advantage on saving throws against spells and other magical effects.

Fiendish Ascension

At 14th level the Fiend inside you produces a physical transformation that makes you closer to itself than a humanoid. when you gain this feature You may choose one of the following benefits. In addition, you gain resistance to necrotic and fire damage even when you aren't raging.

Demonic Horns

Demonic horns grow from your skull giving you a Gore attack dealing 1d10+Str piercing damage. you are proficient with this attack, you may only make one gore attack per turn. if you move 15 feet or more and then hit a creature with a gore attack you may deal an additional 2d10 peircing damage. if the target is a creature they must make a contested athletics check against your athletics or be knocked 10 feet away and prone.

Hellish Wings

Hellish wings erupt from your back when you rage giving you a flying speed of 30ft. if you'r rage stops mid flight you fall to the ground.