Path of Forming

The Path of Forming is a path few would walk. Barbarians of this path have been cursed by an aberration or another being from the outer planes. The barbarians body and form has become malleable and clay like to these outer world beings. Usually, the barbarian is able to control their form, but while raging they cannot control their form, and hand it over to their controllers.

These barbarians can control which forms they'd desire, and their controllers are willing to let them shift as they please, but their rage is forever tainted by this malformed visage.

Form Change

Starting when you choose this path at 3rd level, your rage becomes shaped by the aberrant world, manifesting as forms you take during your rage. At the end of a long rest, you can choose two Forms that your rage can take, the forms are detailed at the end of this feature. Upon entering a rage, choose one of your two chosen forms to gain the benefits of. While you are raging, you can use your bonus action to switch forms, however switching forms grants all enemies within 10 feet of you Advantage on their attack rolls against you until the start of your next turn.

The Ghoul. You grow in size and your skin de-saturates. Your stomach becomes a gaping maw, and your eyes shift into a single eye in the middle of your head. Whenever you down a creature during your Ghoul Rage, you gain a +1 bonus to damage rolls. This bonus can stack, but only applies when you are in a Ghoul Rage and disappears when your rage ends.
The Corrupted. Your body becomes covered with dark purple wood, and twisting tree branches. Pulsating purple energy leaps inside and around you. Whenever you down a creature during your Corrupted Rage, difficult terrain sprouts out from the creature in a 15 foot square. You and your allies ignore this difficult terrain. The terrain persists even when switching forms, and only disappears when your rage ends.
The Predator. You become twisted and mangled, as your bones dislocate and make your body elongate. You gain three extra eyes, as they all become bright green. During your Predator Rage, you gain Dark Vision out to 120 feet, and Blind Sight out to 30 feet. This bonus only applies to your Predator Rage.
The Monster. You fall on all fours and grow white fur. Your mouth shreds open your cheeks, and becomes a sickly snout. While in a Monster Rage, you have advantage on an attack roll against a creature if at least one of your allies is within 5 feet of the creature and the ally isn’t incapacitated. This benefit only applies to your Monster Rage.

Abberant Charge

Beginning at 6th level, you have gained a utility on your movement depending on what form you have taken. When you take the dash action, you gain a small benefit depending on what Form your rage is currently in.

The Ghoul or The Predator. You can run through the space of hostile creatures without penalty, and when doing so those creatures take bludgeoning damage equal to your Rage Damage bonus.
The Corrupted or The Monster. You can run through the space of hostile creatures without penalty, and creatures cannot take attacks of opportunity against you.

Additional Forms

Beginning at 10th level, you gain two additional forms which you could choose at the end of a long rest, in addition to the four you already can pick from.

The Gargoyle. Your skin becomes a dark grey, and your figure thins. You sprout two large black bat wings out of your back, if you already have wings these replace them. While in a Gargoyle Rage, you gain a fly speed equal to your walk speed. If you already had a fly speed, it increases by 30 feet. This benefit only lasts while you are in a Gargoyle Rage, and you begin to fall if you switch Forms while flying.

If you dash in this form, you can run through the space of hostile creatures without penalty, and when doing so those creatures take bludgeoning damage equal to your Rage Damage bonus. 

The Detonator. Your body puffs, and red light begins to pour out from your mouth, ears, nose, and eyes. Your body feels as though it could burst at any moment. When you switch out of this Form, all creatures within 30 feet of you need to make a Dexterity Saving Throw, (DC = 8 + Your Constitution Modifier + Your Proficiency Bonus), taking 3d12 fire damage on a failure or half as much on a success. Once you switch out of this form, you cannot switch back into it until your rage ends.

If you dash in this form, you can run through the space of hostile creatures without penalty, and creatures cannot take attacks of opportunity against you.

Quick Switch

Starting at 14th level, you can quickly switch on the fly. You can switch as a free action on your turn, but you still can only switch once per turn.