Path of the Blazing Heart

Barbarians who tread the path of the Blazing Heart rely not only on their fury and might, but on a core of incredible supernatural power at the center of their very being. This core could be a gift from a greater being, it could be the result of arcane experiments performed on them, it could be their own seething spirit wanting to lash out. Whatever the source, they channel that power through their rage to achieve impossible things, so long as their bodies can handle the toll.

Heart of Fury

Starting at 3rd level, the power at your core has a unique nature and reacts with certain energies. When you gain this ability at third level, choose a damage type for your core between fire, lighting, necrotic, or radiant. You gain resistance to your chosen type of damage.

Fire

Your Heart of Fury blazes with fire.

Lightning

Your Heart of Fury blazes with lightning.

Necrotic

Your Heart of Fury blazes with necrotic energy.

Radiant

Your Heart of Fury blazes with radiant energy.

Blazing Core

At 3rd level, immense energy seethes within you, channeled outward through your fury. While raging, you may perform several abilities which use a number of d4s equal to half your Barbarian level rounded down, called Blaze Dice. After performing one of these abilities, you take damage equal to half the result of the dice, though additional damage dice rolled for a critical hit do not contribute to self damage. This damage cannot be reduced or negated in any way.

Blazing Strike: Once on your turn when you hit with a melee weapon attack or unarmed strike, you can deal additional damage to the target of the type you chose for Heart of Fury equal to a roll of your Blaze Dice.

Blazing Rush: As a bonus action or when entering rage, you can increase your movement speed by a number of feet equal to 5 x a roll of your Blaze Dice until the end of your turn. Your long jump distance also becomes equal to your increased total movement speed, and your high jump distance becomes half of that, neither of which require a running start. 

Blazing Bastion: When a creature other than you within 10 feet of you takes damage, you can use your reaction to reduce the damage taken by a roll of your Blaze Dice. If the damage type matches the one you chose for Heart of Fury, you gain a +3 bonus to your next attack roll.

Ever-Burning

At 6th level, the core within you smolders even outside of battle. Depending on which damage type you chose for Heart of Fury, you gain additional features:

If you already have the skill proficiency you would gain from this feature, you may choose a different skill proficiency from the Barbarian skills list.

Fire

You gain proficiency with Wisdom (Perception) checks and Wisdom saving throws. Also, choose one of your skill proficiencies. Your proficiency bonus is doubled for any ability check you make using the chosen skill.

Lightning

You gain proficiency with Dexterity (Acrobatics) checks and Dexterity saving throws. Also, your walking speed increases by 5ft, and you gain a climbing speed equal to your walking speed.

Necrotic

You gain proficiency with Charisma (Intimidation) checks and Charisma saving throws. Also, you are immune to the Frightened condition, and your maximum hit points cannot be reduced.

Radiant

You gain proficiency with Intelligence (Investigation) checks and Intelligence saving throws. Also, you can cast the Light and Guidance cantrips. Constitution is your spellcasting stat for this.

Enduring Body

At 10th level, the pain that your power causes you as it outstrips your body is no longer enough to put you down. If the self-inflicted damage from using your Blaze Dice would reduce your hit points to 0, you instead drop to 1, then can spend one of your hit dice and regain hit points equal to the result. After you use this feature, your current rage ends.

Twice as Bright

At 14th level, when circumstances turn dire, you can release all restraints on your power, unleashing true devastation at the cost of your own body. When you use one of the abilities granted to you by Blazing Core, you may choose to overload your core. This causes your Blaze Dice for this use of the ability to become d8s, and you take full self damage from using Blaze Dice instead of half. 

You can use this feature a number of times equal to your Constitution modifier, regaining spent uses upon finishing a long rest.