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 when you choose this path at 3rd level, you can go into a Frenzy when you rage. If you do so, for the duration of your rage you can make a single melee weapon attack as a Bonus Action on each of your turns after this one. When your rage ends, you suffer one level of Exhaustion.
While you are in a Frenzy, you may fall deeper into it by expending another use of your rages per day as a bonus action. Your rage timer resets to 1 minute, and you may make two melee weapon attacks as a Bonus Action on each of your turns instead of one. You also add your rage damage bonus an extra time to your weapon attacks each time you do this, but you also suffer one additional level of Exhaustion for each once your rage ends.
Regardless of how many times you fall deeper into a Frenzy, if you are still raging five minutes after you initially entered your rage, it immediately ends.
Deep Rest
Also at 3rd level, you may "Sleep Like a Log" when you take a long rest. If you do, you lose two levels of exhaustion instead of one. Also, you cannot be woken from your long rest except by finishing it completely, taking damage, or if someone uses their action to shake you awake.
Additionally, when you take a short rest, you can forgo gaining hit points on one of the hit dice you expend to lose a single level of exhaustion.
Adrenaline
Beginning at 6th level, you do not suffer the effects of the Charmed, Frightened, Grappled, or Exhaustion conditions while raging. You can still have these conditions inflicted on you, but you ignore their effects until your rage ends.
Also, you may still be effected by the Grappled condition if three or more creatures are grappling you, or a creature that is two or more sizes larger than you grapples you.
Intimidating Presence
Beginning at 10th level, you can use your action to frighten someone with your menacing presence. When you do so, choose on creature that you can see within 30 feet of you. If the creature can see or hear you, it must succeed on a Wisdom saving throw (DC equal to 8 + your proficiency bonus + your Rage bonus) or be Frightened of you until the end of your next turn. On subsequent turns, you can use your action to extend the Duration of this effect on the Frightened creature until the end of your next turn. This effect ends if the creature ends its turn out of line of sight or more than 60 feet away from you. If the creature succeeds on its saving throw, you can't use this feature on that creature again for 24 hours.
Retaliation
Starting at 14 level, when you take damage from a creature that is within 5 feet of you, you can make a melee weapon attack against that creature, once this feature is used you can not use it until the start of your next turn. When you reach level 18 you can use this feature twice before the start of your next turn.