Path of the Parasite

Barbarians are known for going to extreme lengths to gain the upper hand in battle. Some barbarians take those extreme lengths to dangerous and terrifying levels, however. Path of the Parasite barbarians allow their bodies to become host to a deadly swarm of parasitic creatures that enhance their physical prowess. Over time, these barbarians become nothing short of shambling husks, walking hives for their uncontrollable infestation. All barbarians want that extra edge, but the Path of the Parasites asks 'how far are you willing to go?'

Hatchery

For the duration of your rage, the awakened parasites swarming all over your body constantly search for other sources of food. Whenever you deal melee damage to a creature, some of your parasites crawl into the open wound you created, burrowing deep under the skin of the creature.
A creature damaged this way gains a "Parasite" stack. Creatures with Parasite stacks take 1d4 necrotic damage per stack at the start of their turn. A creature infested with Parasite stacks may use an action on their turn to deal 2d10 slashing damage to themselves to carve out the tunneling parasites. If they do so, they remove all stacks.

Deadly Host

Whenever you enter a rage, you may choose to lose up to 5 points of your Armor Class. When you do so, unnecessary body parts slough off and fall to the ground while your striking arm becomes reinforced with fibrous membranes. For the duration of your rage, any melee weapon attack you make deals bonus necrotic damage equal to the amount of sacrificed armor class you chose. Your Armor Class returns to normal when your rage ends.

Parasitic Perfection

Whenever a creature deals melee damage to you, it gains a Parasite Stack. In addition, you now implant two Parasite Stacks instead of one from the Hatchery feature.

Assimilation

Whenever a creature ends their turn within 20 feet of you, you may have that creature gain three Parasite Stacks. In addition, your parasites have evolved grasping hooked tendrils and barbs to stay put within these new hosts. A creature must now deal 3d12 slashing damage to dig out these more persistent parasites.