Tempest

Whether they were struck by lightning as a child or inherited their spark of power from a parent or ancestor, tempests are a special sort of berserker. Often raised and trained by druids and other followers of nature, they have both the power of and protection from the elements of the raging storm.

Touched by Thunder

Beginning at 3rd level when you choose this archetype, you can empower a melee weapon you touch while raging. For the duration of your rage, as long as you are holding it the weapon deals an extra 1d6 lightning or thunder damage (your choice when you begin raging). The damage increases to 2d6 at 10th level, 3d6 at 15th level, and 4d6 at 20th level. Only one weapon can be empowered at a time, though you can use a bonus action to transfer the effect to a different weapon. 

In addition, you gain resistance to either thunder or lightning damage. Once this choice is made it cannot be changed.

Whirling Winds

Starting at 6th level, a gale whips up around you as you rage, kicking up grit and debris that make you difficult to see. These winds act as an aura extending 10 feet from you in every direction, but not through total cover. While you are raging, treat all attacks against you as though you had half cover (+2 to AC, Dexterity saving throws , and ability checks made to hide).

In addition, you gain resistance to either thunder or lightning damage, whichever you did not choose at 3rd level.

Forceful Gale

Starting at 10th level, the winds of your aura make it difficult for creatures to keep their feet. Once per turn while raging, when you damage a creature with a melee attack you can force the target to make a Strength saving throw (DC 8 + your proficiency bonus + your Strength modifier). On a failure the creature is pushed 10 feet away in a direction of your choosing. This distance stacks with any forced movement caused by a Furious Critical.

Perfect Storm

Starting at 14th level, any hostile creature that begins its turn inside your Whirling Winds aura makes a Constitution saving throw (DC 8 + your proficiency bonus + your Strength modifier). The creature takes thunder or lightning damage (the same type as Touched by Thunder) equal to your berserker level on a failed save, or half as much on a successful save.