Path of the Deathless

Throughout time, people have found themselves fascinated by the barrier between life and death. Barbarians that choose to follow the Path of the Deathless take this fascination and embrace it as the core of their very being. Maybe your character had a brush with death earlier in life, either through necessity or by foolish actions taken while escaping the drudgery of every day life. In either case, the rush of battle as death neared fueled you, and as blood rushed through your body to power through adversity, it became obvious that you must feel this way again. It is sometimes said that no person seeks out the Path of the Deathless, but rather than the Deathless are born this way and only find out their true natures by pushing their limits ever further.

Blood in the water

When you enter rage, you take damage equal to your proficiency bonus + 1d6. While raging, if your current HP are less than half your maximum, you deal an additional 1d6 damage per successful attack. 

Keep Fighting

Starting at level 6, you gain advantage on Constitution saving throws while raging.

Grim Warrior

Starting at level 10, any weapon you wield (including unarmed and improvised attacks) is considered magical for the purposes of damaging undead.

Stoic

Starting at level 14, if reduced to 0 HP while raging, you remain conscious until you fail two death saving throws or your rage ends, whichever happens first. You become immune to becoming frightened or stunned.