Primal Path: Berserker
For some barbarians, rage is a means to an end -- that end being violence. The Path of the Berserker is a path of untrammeled fury, slick with blood. As you enter the berserker’s rage, you thrill in the chaos of battle, heedless of your own health or well-being.
Frenzy
Starting at 3rd level, you gain an additional use of your Rage feature. When you enter your rage or as a bonus action while raging, you can enter a frenzied rage. While in a frenzied rage you can make an additional attack as part of the attack action and your rage damage bonus is doubled. When you exit your frenzied rage you gain 1 point of exhaustion.
At 10th level you gain another use of your rage feature.
Mindless Rage
Beginning at 6th level, you can’t be charmed or frightened while raging. If you are charmed or frightened when you enter your rage, the effect is suspended for the duration of the rage.
In addition while you are not raging you have advantage on saves against charmed or frightened effects.
While raging you ignore the effects of exhaustion.
Intimidating Presence
Beginning at 10th level, you have advantage on intimidation checks and can use your strength modifier in place of charisma for intimidation checks.
While raging you can use your action to let out an intimidating roar. Choose any number of creatures you can see within 30 feet of you to make a wisdom saving throw, on a failure they are frightened of you for 1 minute and can repeat the save at the end of each of their turns, ending the condition on a success. You can use this feature once per rage and it counts as an attack for the purposes of maintaining your rage.
In addition when you kill a creature you can choose any number of creatures within 30 feet of you to make a wisdom saving throw, if the killing blow was a critical hit they make the save with disadvantage. On a failure they are frightened of you for 1 minute and can repeat the save at the end of their turns ending the condition on a success.
The DC for this feature is 8 + Proficiency Bonus + your Strength modifier.
If the creature succeeds on its saving throw against any of these effects, it's immune to this feature for 24 hours.
At 15th level the range of these features extends to 60ft.
Retaliation
Starting at 14th level, when you take damage from a creature that is within your melee range. You can use your reaction to make a melee weapon attack against that creature.
If a creature scores a critical hit against you you have advantage on attack rolls against that creature until the end of your next turn.