Path of the Slayer

Fueled by an unbreakable will and the rage to match, those who would choose the Path of the Slayer devote their existence to a single, relentless purpose. In this quest there is no peace or respite, only the broken bodies of those who would stand in your way. Theirs is the path of perpetual torment, their souls blistered by ravenous fury and tainted beyond redemption.

Unrelenting

When you choose this Path at 3rd level, your unbridled rage and determination can keep you going when others would falter. While raging you can use a bonus action to spend a number of hit dice up to half your barbarian level. For each die spent you regain a number of hit points equal to your constitution modifier.

Feed the Fury

Also at 3rd level, the act of slaughtering your foes fuels your conviction. Whenever you reduce a hostile creature to 0 hit points, you regain a number of barbarian hit dice equal to half the creature's challenge rating (minimum of 1).

Incorruptible

By 6th level, your iron resolve overcomes any attempts to sway you from your course. While raging you are immune to spells and effects that would force you to act against your will, such as the Dominate Person spell, or a Ghost's Possession ability. Additionally, you ignore any effect that would prevent you from attacking a creature, such as the Sanctuary spell or Charmed condition. 

Blood Strike

Starting at 10th level you can use your own vitality to imbue your attacks with relentless fury. Once per turn when you hit a creature with a melee attack, you can spend a number of hit dice up to your Constitution modifier. Each creature within 5 feet of the target (other than you) must make a Constitution saving throw (DC equal to + your proficiency bonus + your Constitution modifier) or take 1d12 force damage for each hit die spent and be knocked prone. On a successful save a creature takes half damage and is not knocked prone.

Rip and Tear

Beginning at 14th level, your terrible wrath can eviscerate lesser foes. When you hit a melee attack while raging, you can instantly reduce the target to 0 hit points if its current hit points are equal to or lower than your strength score.