Warriors who draw strength from their pain, these risk-driven barbarians unlock greater powers as they drive themselves to the edge of death. 

Changelog:

 Defiant Hope changed to only give +1d4 to a saving throw once per turn, instead of +1d4 to all attack rolls and all saving throws every turn. It outclassed the Defiances specifically made for extra damage in terms of damage, and then it also had a big boost to saves too.

Changed Defiant Life to only give temporary HP. Having multiple Barbarians with both Defiant Life and Defiant Bloodlust would become absurd.

Inflammation wears off at the start of your turn instead of at the end of your turn, but now explicitly ignores the usual limit on active Defiances.

Added a failsafe for if you have more than your maximum active Defiances active at the end of your turn.

Changed some language and formatting to match official wording.

Defiance

Starting when you choose this path at 3rd level, You gain your choice of 3 of the following Defiance features; you gain additional ones at level 10, and you can swap out one known whenever you level up. Defiance features activate whenever your HP falls below half and you are raging, and deactivate at the end of your turn if your current HP is greater than half its maximum or you are not raging. You may only have two known Defiance effects active at once, but as a free action during your turn you may switch which are active.

Defiant Bloodlust

10th level. While you channel Defiant Bloodlust, you heal a number of Hit Points equal to half your proficiency bonus (rounded down) the first time you land a hit with a melee weapon attack each turn. This healing cannot heal you over half your maximum Hit Points.

Defiant Eruption

While you channel Defiant Eruption, your weapon attacks can deal your choice of fire, ice, lightning, or poison damage instead of their normal damage type. In addition, your weapon shines with elemental energy, emitting bright light out to 10 feet and dim light out to 30 feet.

Defiant Focus

While you channel Defiant Focus, you may use your bonus action to mark a creature you can see within 60 feet for one minute. Your critical hit range is expanded by one, and you heal a number of Hit Points equal to your Constitution modifier (min: 1) when the marked creature dies. In addition, when the marked creature dies, you may move your mark to another creature within 60 feet. You may only have one creature marked at a time.

Defiant Growth

10th level. While Defiant Growth is active, your size doubles in all dimensions, along with anything you are wearing, and your weight increases by eight times. Your size doesn't change if there isn't enough space for you to do so. In addition, your weapons also enlarge, and your attacks deal 1d6 additional damage.

Defiant Hope

While you channel Defiant Hope, you can add 1d4 to a saving throw once per turn.

Defiant Life

10th level. While you channel Defiant Life, all other creatures you choose within 30 feet gain a number of temporary Hit Points equal to half your proficiency bonus when you take damage.

Defiant Physics

10th level. While you channel Defiant Physics, you gain a 30 ft flying speed, and you are also immune to the Grappled and Restrained conditions.

Defiant Resilience

While you channel Defiant Resilience, you gain resistance to your choice of fire, ice, lightning, or poison damage.

Defiant Strength

While you channel Defiant Strength, when you hit with a weapon attack, you may reroll any number of damage dice and use the higher sum.

Defiant Swiftness

While you channel Defiant Swiftness, you gain 15 additional feet of movement speed, and can take the Disengage action as a bonus action.

Defiant Toughness

While you channel Defiant Toughness, all incoming damage is reduced by 3. (Damage reduction occurs before damage resistances are factored.)

Defiant Vengeance

While you channel Defiant Vengeance, enemies take necrotic damage equal to half your proficiency bonus (rounded down) when they hit you.

Refusal

Starting at 6th level, when you would regain Hit Points, you can choose to gain an number of temporary Hit Points equal to the amount you would have healed instead of regaining Hit Points (no action required).

Inflammation

Also starting at 6th level, as a bonus action, you can take psychic damage equal to one Barbarian Hit Dice and channel one of your known Defiances. This damage cannot be resisted or reduced in any way. This Defiance effect will last until the start of your next turn.

Greater Defiance

At 10th level, you learn 2 additional Defiances. You may also now have up to 3 known Defiances active at once.

Last Straw

Starting at 14th level, whenever you take damage, you may channel one of your known Defiances as a reaction until the end of your next turn.