Path of Insanity

This class gives barbarians a psionic skill set caused by arcane insanity. With these abilities, you are a force to be reckoned with. Weather is be through devastating  psychic damage, becoming resistant to mind altering affects, or bringing psychic fear to your foes, you are indeed a mad animal to be afraid of.

Release the Madness

At 14th level, as a bonus action, you may choose to end your rage to release a 15 ft radius sphere of maddening energy. Each creature in that area must make a Wisdom saving throw equal to 8 plus your constitution modifier plus your proficiency. If they fail, the creature takes 4d10 psychic damage, and becomes frightened for 1 minute. On a successful save, the creature takes half damage.

This damage increases to 5d10 at 19th level.

Unhinged Insanity

At 3rd level, while raging, you may use a free action once per turn to add 2d6 psychic damage to one of your attacks, until your rage ends.

This damage increases to 3d6 at 6th level, 4d6 at 10th, 5d6 at 14th, and 6d6 at 19th.

Clouded Anger

At 6th level, while in rage, you have resistance to psychic damage and advantage on wisdom saving throws.

At 14th level, while raging you are immune to psychic damage and immune to being detected by spells, or your thoughts and memories being detected or altered by spells.

Shared Pain

At 10th level, as a reaction, you may cause the creature that attacked you to take psychic damage equal to the amount of damage they dealt to you.