Burning Blood

A Burning Blood fighter can opt to use a fiendish attack to do more damage, at the cost of increasing the chance of rolling a crit fail. The fighter can also use an ability an amount of times equal to their proficiency modifier to transfer fiendish energy to an enemy, dealing bonus damage. Other benefits that come from Burning Blood include burning off poisons and adding other bonuses to the amount of fiendish energy burnt off.

Fiendish Channel

Beginning when you take this archetype, a Burning Blood Fighter can use a fiendish attack in order to deal an extra 1d4 damage on an attack. Each use of Fiendish Attack adds an instance of Fiendish Energy that increases a the range of a crit fail occurring by 2 on a d20 roll to attack, which resets after each combat or whenever Fiendish Channel is used. Halflings start at 0 instead of 1. Fiendish Channel can be used an amount of times equal to the proficiency bonus, and consumes each Fiendish Energy to do an extra Xd4 damage per energy consumed. You can not have more than 9 instances of Fiendish Energy. All Fiendish Energy is lost on a crit fail.

Reaping Strike

Using an action, you may place one mark per instance of fiendish energy on any amount of enemies within 30 feet of you, and then detonate each mark dealing Xd6 damage per mark. You may heal for half of this damage an amount of times equal to your proficiency modifier per short rest.

Demon Form

As an action, you may enter a demonic stance that grants 2 strength and takes 1d6 + half your character level as damage each turn to maintain. This form lasts up to a minute, and can be used a number of times equal to your proficiency bonus per long rest.

Demonic Channel

Each Fiendish Channel only increases the range of a crit fail by 1, instead of 2.

Corrupted Offering

Reaping strike is now a bonus action, and consuming fiendish energy is now a free action.