The Path of The Mountain Lord

The Mountains are dangerous places, if it isn't monsters to look out for, it is the beasts that in habit them, the harsh weather or the long falls into an abyss. Some Barbarians however, choose to dwell in such places and have gone down a path to make them as enduring and unforgiving as the mountains they inhabit. 

Avatar

Beginning at the third level, When you rage, you gain temporary hit points equal to your barbarian level x 5. When your rage ends you lose all temp hit points. You are also immune to poison effects, poison damage, disease, and petrification. Any effects from a poison, disease, or petrification that are on you do not affect you while you rage.

Thunderstomp

Beginning at the 6th level, you may forgo one of your attacks on your turn to slam the ground with such force that it creates a shockwave. All enemies within 5 feet of you must make a Dex save equal to 8 + your con modifier + your proficiency on a failed save targets take 1d6 thunder damage and are knocked prone. This damage is increased to 2d6 at the 10th level, and 3d6 at the 15th level, and 4d6 at the 20th level. This counts as making an attack for the purposes of maintaining rage

Bash

Beginning at the 10th level, whenever your critical hit with a weapon, whoever you hit must make a con save equal to 8 + your Con Mod + your proficiency or be stunned until the start of their next turn.

Hammer of The Mountain

 Beginning at the 14th level, once per rage, you may throw a magic hammer infused with thunder at the opponent as a bonus action. They must succeed on a Constitution save equal to 8 + your con modifier + your proficiency or take 4d6 thunder damage and be stunned until the end of your next turn. Targets who make the save only take half damage and are not stunned