Path of Blood

Trading deadly blows with your enemies is the absolute greatest pleasure you know. Using your own wounds to motivate and bolster your own retaliatory attacks, not only do you feel comfortable with the pain, you seek it out. As long as you draw breath you can keep up the assault, but the closer you are to the brink, the more enjoyable the encounter becomes.

Blood Fueled Rage

Beginning at 3rd level, the lower your hit points are, the more damage you can deal while raging. If you are below your hit point maximum while raging, your attacks deal an extra 1d4 points of damage, if you are at or below half it becomes 1d6. If you are below one-quarter the extra damage is also dealt to any creatures of your choice that are both within 5 ft of your target and within reach of your weapon as you swing with reckless abandon in your last stand.

At 10th level, the damage at each tier becomes 2d4 and 2d6 respectively. At 14t they become 3d4 and 3d6.

Masochist

Also at 3rd level, as a bonus action or when you activate rage, you can disable your resistance to bludgeoning, piercing, and slashing damage. You can later re-enable it as a bonus action.

Share the Pain

Starting at 6th level, you can mitigate some of the damage you take and redirect it to the next creature you hit. Whenever you take damage from a hostile creature while raging, you can use your reaction to reduce the damage by up to half your Barbarian level plus the dice you can currently roll for Blood Fueled Rage. The next time you hit a creature with a strength-based attack before the end of your next turn, you can deal additional damage to it equal to the damage you absorbed with this ability.

You can use this ability a number of times per long rest equal to your Constitution modifier (minimum of 1). Additionally, when you take damage that would reduce you to 0 hit points you regain 1 use of this ability. You can regain a number of charges in this way equal to your Constitution modifier (minimum of 1), at which point you must complete a long rest to regain more.

Fast Recovery

Upon making it to 10th level, you have become very accustomed to the cycle of pain and recovery. Whenever you roll hit dice to heal during a short rest, treat any roll of 5 and below as a 6. Additionally, when rolling death saving throws, you regain 1 hit point on a roll of 19-20.

Pain Suppressant

At 14 level, you've discovered that a heavy shock of self-inflicted pain causes any other income damage to seem muted in comparison. As a bonus action or when you activate your rage, you can sacrifice half your current health to resistance to all damage (except psychic) for one minute. Additionally, if your health is at or below 1/4 remaining while this effect is active, you cannot be critically hit by an attack.