Path of the Wrathful Specter

Channeling the fury of spirits from beyond the grave to fuel their rage, those barbarians who follow this Primal path are terrors on and off the battlefield. The anguished screams of the departed, intangibility, invisibility, floating, this path provides many unnatural abilities.

Ghastly Wail

At 3rd level, you can channel the blood curdling screams of the departed.

As an action, you can release a terrifying wail. All creatures within 20 ft. of you must make a Wisdom saving throw, the DC of which is equal to 8 + your Proficiency bonus + your Constitution modifier. On a failure, an affected creature is Frightened of you for 1 minute. A frightened creature can repeat its saving throw at the end of each of its turns, ending the effect on itself on a success. 

As long as there is at least one creature that is frightened of you in this way, and you are raging, your rage does not end early.

You can use this feature once before you must finish a long rest. When you reach 10th level, you gain an additional use of this feature, and its range increases to 30 ft.

Poltergeist

Also at 3rd level, when your rage fades, so do you.

When your rage ends, you can choose to become invisible for the next 10 minutes or until you damage another creature.

Ghostly Figure

Starting at 6th level, your body becomes ghostly and ethereal while you rage.

While raging, you gain resistance to acid, cold, fire, lightning, necrotic, poison, and thunder damage. Moreover, if you are grappled or restrained by nonmagical means, you can expend half your movement to escape from the grapple or restraints.

Spectral Sprint

At 10th level, you gain the ability to fly through solid objects. 

While raging, you have a flying speed equal to your walking speed, and can move through objects and creatures as if they were difficult terrain. If you end your movement inside a creature or object, you take 1d12 force damage and are shunted to the nearest unoccupied space.

Return from Death's Door

By 14th level, you have lingered on the threshold of death for so long that you can step back when others would be sucked through its fatal frame.

You cannot be killed outright by damage, and only fail death saving throws if you roll a 5 or lower on the d20. Moreover, if you roll an 18 or higher on a death saving throw, you stand up with 1 hit point, and can use your Ghastly Wail feature without using an action, even if you have no uses of that feature remaining.