Path of the Far Beyond

While some barbarians draw their power from an inherent primal rage that burns within, from the guiding spirit of their ancestors, or from the very elements of the world, some pull from a power far more esoteric. Through dark ritual, kidnapping, or simple happenstance, these barbarians have gazed into the Far Beyond, and have been permanently changed. Their rage is born from desperation, a scream from the effort of holding together a fragmenting consciousness.

The Void Stares Back

When you rage, your eyes roll up and become portals to the Far Realm, and anyone who meets their gaze feels the terror of the incomprehensible. While raging, you can cast the cause fear spell without using a spell slot or components. Constitution is your spellcasting ability for this spell. Your save DC for this spell (and other subclass features that require a save) equals 8 + your Constitution modifier + your proficiency bonus.

You can use this feature a number of times equal to your Constitution modifier (minimum of once). You regain all expended uses when you finish a long rest.

Remnants of the Unknowable

Starting when you choose this path at 3rd level, you gain the ability to summon the essence of the Far Realm itself when you attack. While you're raging and you use the attack action against an enemy you may, as a bonus action, besiege your foes with a burst of eldritch energy. This burst of energy inflicts 1d4 psychic damage on a successful hit (using the same to hit bonus as your weapon).

The damage increases when you reach certain levels: 1d6 at 8th level, and 1d8 at 14th level.

Diffusion of Esoteric Truth

Beginning at 6th level, you begin to exude the aberrant miasma of the Far Realm itself. While raging, you are resistant to psychic damage.

Additionally, you can, as an action, cause the miasma to pulse, encompassing the area around you. For 1 minute, your form wavers incomprehensibly, and when anyone targets you with the attack action, you roll a d20 to see if they succeed, or attack a place they thought they saw you standing. If you roll a 10 or higher, they attack your afterimage. 

You can use this features a number of times equal to your Constitution modifier (minimum of once), and regain all spent uses when you finish a long rest.

Friends in Far Places

At 10th level, you gain the ability to summon the aid of aberrations from the Far Realm. As an action, choose one creature within 60ft. This creature must succeed on a Dexterity saving throw or becomes grappled by strange tentacle-like appendages for 1 minute. As a bonus action, you can cause aberrant energy to surge through the tentacles, dealing 2d4 psychic damage to the grappled creature. The creature may attempt an Athletics check against your Save DC at the end of each of its turns to escape the grapple.

Once you use this feature, you may not use it again until you have finished a long rest.  

Aberrant Equilibrium

You have become fully attuned to the Far Realm. While you are raging, you become immune to psychic damage and have advantage on saving throws against mental effects.

Additionally, you may spend an Action to call forth the stars themselves to aid you in battle.You gesture to a point within 60ft, the air above which rips open to allow for an extraterrestrial barrage. Each creature within a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. On a failed save, the target takes 6d6 bludgeoning damage and 3d6 psychic damage, and is knocked prone, or half as much on a successful save and are also not knocked prone. 

Once you use this feature, you may not use it again until you have finished a long rest.