Path of the Abyss

Demons do not possess the bodies of Barbarian belonging to the Path of the Abyss, instead the fiends share the barbarians body with the barbarians very soul, using the body as a vessel as an instrument for violence, much like a puppet and its master. Path of the Abyss barbarians often find there body going against there own will, as if they were being yanked and contorted towards the most cruel actions imaginable, but having a demon that wants to use you has its benefits.

Puppets Leash

The demon inside of you will not let its vessel be killed, this manifests in death never truely being able to take you, atleast without the most mortaling of blows.

Additionally. when you are healed the demon feasts on the magic and heals you more as a reward. All healing you recieve is increased by your condition modifier.

Unceasing Rage

Starting when you choose this path at 3rd level when you are in your rage, the demon within grasps onto your very being, making you harder to sever from this mortal realm. When you fall to 0 hit points, instead of falling unconscious you instead remain conscious but are still considered dying and still need to make death saving throws as normal.

You can attempt to stabilise yourself as described in the rules. When you are stabilised you gain one hit point instead of remaining at zero.

Hellish Strikes

Beginning at 6th level, when you hit a target with a melee weapon attack from an action you can choose to take 1d4 necrotic damage (this damage cannot be reduced by any means) to increase the attack by 3d4 necrotic, fire or cold damage (your choice).

Rage of Demons

From 10th level onwards, you can channel the demon within you to affect somebody else with the same bloodlust that claws at the back of your mind. As an action, you can cause a creature within 120 feet to go into an unfettered rage. The target makes a Wisdom check equal to 8 + your Constitution modifier + your proficiency bonus, on a failed save the target is affected by a level 1 Barbarians Rage feature, as described in the Player's Handbook. It lasts a maximum of 5 minutes and a minimum of 1 minute (the target attempts to maintain the effects (i.e. kill everything in sight). You can use this feature a number of times equal to your Constitution modifier per long rest.

Feeding Frenzy

Starting at 14th level, you may consume the life essence of what you kill instead of the demon, the soul no longer bound to an endless service in The Wastes. Whenever a creature is killed within 30ft. of you, you heal hit points equal to the creature's level x 4 or their Challenge rating x 2. You do not gain this benefit from fiends, undead, or constructs.