Juggernaut Symbiote

Some barbarians derive their power from a source originally alien to their body, which gradually becomes a part of them. Their rage isn't truly a reflection of any kind of primal anger, or hatred of the world; rather, it is them controlling the power of the parasite that lives inside of their body.

There are many beings which could grant a barbarian such powers, either through their anatomy alone or from some sort of magical abilities. Some examples include an oblex that was too weak to fully devour the body, a mind flayer tadpole that was unable to reach the brain, or some sort of demonic mutation that gained a faint bit of sapience.

Symbiote Shell

When you choose this path, at 3rd level, you form an organic shell around your body when you enter a rage. For the duration of your rage, you gain the following benefits:

• Your AC increases by 1 provided you aren't wearing armor.
• Your unarmed strikes deal slashing damage equal to a monks martial arts die. When you take the Attack action and make an unarmed strike while not wielding a shield, you can use your bonus action to make an unarmed strike.

Your symbiote shell might be obvious at a glance, such as black armor-like covering around your body that enlarges your teeth and gives you a threatening look, or it might be something more subtle, such as your fingernails (or fingers) turning into scythe-like blades.

Primal Fling

Beginning at 3rd level, you can use your symbiote's unnatural anatomy to perform a horrifying technique.

Once per turn, when you hit a creature with an unarmed strike, you can use the following technique. The DC is equal to 8 + your proficiency bonus + your Strength modifier.

Primal Fling. Your arm's muscles expand to be larger than your body, and allow you to toss the creature. The creature must succeed on a Strength saving throw, or be thrown up to 15 feet away from you. A Large or larger creature automatically succeeds on its saving throw.

Warshaper

Starting at 6th level, your symbiote begins to define itself more clearly, granting you a new ability. Choose one of the following features:

Expanded Biomass. While raging, you count as one size larger for the purpose of grappling, and a creature only automatically succeeds on its saving throw against your Primal Fling if it is Gargantuan.

Warped Reach. While raging, your unarmed strikes have the reach property. Additionally, you can grapple and shove creatures that are 10 feet away from you. If you successfully grapple a creature that is further than 5 feet away from you, you immediately pull it to be within 5 feet of you.

Alien Strikes

Additionally, at 6th level, the otherworldly nature of your shell makes your unarmed strikes count as magical for the purpose of overcoming damage resistance and immunity. 

Apex Predator

By 10th level, your connection to your parasite influences your mind, making you think and act like it does. Other creatures have disadvantage on Wisdom (Insight) checks made to read your emotions or tell if you're lying, and you have advantage on Wisdom (Survival) checks made to track a creature without all of its hit points.

Healing Factor

At 14th level, your flesh has fully fused itself with your symbiote, making it regenerate at unnatural speeds. At the start of each of your turns, you regain hit points equal to your Constitution modifier if you have no more than half of your hit points left. You don't gain this benefit if you have 0 hit points.

Additionally, if you put a severed body part of yours back in place as an action, the part reattaches