Path of the Hellrager

Barbarians in their most savage form, tainted and train in the pits of Avernus and send to the material plane to erase those who oppose them. 

Appetite for Destruction

Starting at 3rd level, you feed on the despair your strikes inflict to push them further. Once per turn, when you score a critical hit or reduce a hostile creature to 0 hit points, you may make an additional melee weapon attack as part of the Attack action on your turn. This attack does not count against the number of attacks you can make with the Extra Attack feature.

In addition, whenever a hostile creature scores a critical hit against you, your next weapon attack against it is a critical hit. 

Infernal Boon

Also at 3rd level, you receive hell's blessing to unleash destruction upon the world. You learn how to read, speak and write Infernal, and you gain proficiency in the Intimidation skill. You may use your Strength modifier instead of your Charisma modifier for ability checks using that skill.

Sacrilegious Strike

When you reach the 6th level, the destruction you leave in your wake is unmendable. Whenever you hit a creature with a weapon attack, you can force it to unleash its inner destruction. It must make a Wisdom saving throw (DC - 8 + your Constitution modifier + your proficiency bonus). On a failure, you can choose to inflict it with one of the following effects:

• It feels the need to unleash violence. On its next turn, it must use its action to make a weapon attack. If the attack is made against anyone other than you, it takes 1d10 fire damage.

• Its inner rage is boundless. It takes 2d10 fire damage, and the next weapon attack the creature makes against you is a critical hit.

You can use this feature a number of times equal to your Constitution modifier (a minimum of once. You regain all expended uses when you finish a long rest.

Skullsplitter

Also at 6th level, you are capable of incredible bursts of violence. Your weapon attacks score a critical hit on a roll of 19 or 20. Starting At 14th level your weapon attacks score a critical hit on a roll of 18, 19 or 20.

Running on Rage

When you reach 10th level, you find meaning in the symphony of destruction you wreck upon the world, and refuse to let such a violent melody end. While conscious, critical hits cannot reduce you below 1 hit point.

Infernal Bloodlust

By the 14th level, your bloodlust cannot be quenched nor killed. When you fall under half your maximum hit points, you may expend your reaction to gain the benefits of the haste spell. These last for 1 minute and do not require your concentration, nor does this count as a spell for the purpose of dispelling or countering magic. Whenever you score a critical hit while under the effects of this feature, you refresh its duration, up to a maximum of 10 minutes.