Path of the True Berserker

In battle, these warriors are renowned for their fits of frenzy. They would howl like wild beasts, foamed at the mouth, and gnawed the iron rim of their shields. According to belief, during these fits they were immune to steel and fire, and made great havoc in the ranks of the enemy. These barbarians that walk this path use their rage, ferocity and attunement with the wilds to project an animal form similar to a way druids do. However these forms are dark and twisted not using discipline or practice to achieve but instead sheer unadulterated rage. It is said that these warriors can sometimes go to far and lose themselves to the beast, never to return to their humanoid form.

These warriors are rare but when gathered they are devastating to any battle, these barbarians often wore special clothing, for instance furs of a wolf or bear, to indicate that this person was "Shape-Strong", and would not be able to tell friend from foe when in a frenzy. In this way, other allies would know to keep their distance from these titans of battle.

Animalistic Fury

Starting when you choose this path at 3rd level, when you use your rage you can change your physical shape and attributes to match those of the beasts that walk the land like the warriors of old.

Your barbarian level determines the beasts you can transform into, as shown in the Beast Shapes table. At 3rd Level, for example, you can transform into any beast that has a Challenge rating of 1/4 or lower that doesn't have a flying or swimming speed.

Table: Beast Shapes
Level Max. CR Limitations 
2nd 1/4 No flying or swimming speed
4th 1/2 No flying speed 
8th 1 — Giant Eagle flying speed permitted

you can stay in a beast shape for a number of hours equal to half your barbarian level (rounded down). You then revert to your normal form unless you expend another use of this feature. You can revert to your normal form earlier by using a Bonus Action on Your Turn. You automatically revert if you fall Unconscious, drop to 0 Hit Points, or die.

While you are transformed, the following rules apply:

- Your game Statistics are replaced by the Statistics of the beast, but you retain your Alignment, personality, and Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw Proficiencies, in addition to gaining those of the creature. If the creature has the same proficiency as you and the bonus in its stat block is higher than yours, use the creature's bonus instead of yours. If the creature has any legendary or Lair Actions, you can't use them.

- When you transform, you assume the beast's Hit Points and Hit Dice. When you revert to your normal form, you return to the number of Hit Points you had before you transformed. However, if you revert as a result of Dropping to 0 Hit Points, any excess damage carries over to your normal form. For example, if you take 10 damage in animal form and have only 1 hit point left, you revert and take 9 damage. As long as the excess damage doesn't reduce your normal form to 0 Hit Points, you aren't knocked Unconscious.

- You can't cast Spells, and your ability to speak or take any action that requires hands is limited to the capabilities of your beast form.

- You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can't use any of your Special Senses, such as Darkvision, unless your new form also has that sense.

- You choose whether your Equipment falls to the ground in your space, merges into your new form, or is worn by it. Worn Equipment functions as normal, but the DM decides whether it is practical for the new form to wear a piece of Equipment, based on the creature's shape and size. Your Equipment doesn't change size or shape to match the new form, and any Equipment that the new form can't wear must either fall to the ground or merge with it. Equipment that merges with the form has no Effect until you leave the form.

- You can use weapons that your form can reasonably use.

-  If you begin your turn with no more than half of your maximum hit points, you must succeed on a DC 8 Wisdom saving throw or move directly towards the nearest creature to you and use the Attack action against that creature. You can choose whether or not to use your Extra Attack feature for this frenzied attack. If there is more than one possible target, roll to randomly determine the target. You then regain control for the remainder of your turn.

Fury Incarnate

Beginning at 6th level,  you can transform into a beast with a challenge rating as high as your barbarian level divided by 3, rounded down. You also gain temporary HP equal to your barbarian level when you rage and your unarmored defense bonus can be used in your beast shape if you choose.

Unending Bloodshed

Beginning at 10th level,  You can hunt any foe, foiling their attacks and punishing them for daring to prey on others. When you hit a creature with a melee weapon attack, you can mark the creature until the end of your next turn. This effect ends early if you are incapacitated or you die, or if someone else marks the creature.

Until the mark ends, any creature attacking a marked creature deals an extra 1d6 psychic damage to the target whenever they hit it with a weapon attack and trigger a special reaction that you can use the amount of times equal to your strength modifier. With this special reaction you can make one opportunity attack against a creature within your reach, you can do this at the end of every creature's turn, except your turn. If the target drops to 0 hit points before this effect ends you can move the mark to other hostile foes within 30ft of the creature.

You regain the uses of your special reaction at the end of a short rest.

Shape-Strong

Starting at 14th level, If you take damage that reduces you or your wildshape form to 0 hit points while raging, you can use your reaction to delay falling unconscious, and you can immediately take an extra turn. While you have 0 hit points during that extra turn, taking damage causes death saving throw failures as normal, and three death saving throw failures can still kill you. When the extra turn ends, you fall unconscious if you still have 0 hit points.

Once you use this feature, you can’t use it again until you finish a long rest.