From publisher blurb:
Although many barbarians draw power from the world of spirits through their use of primal totems or unwavering devotion to an ancestral tradition, some embrace a more dangerous path. During a rage, barbarians who follow the Path of the Hollow Self leave their bodies empty vessels open to any wrathful or malevolent spirits who may find it. These fugues rely upon necromantic powers that even the most accomplished of arcane masters may dismiss as too dangerous, as there is little way to tell what nightmarish forces may rally when a strong new body presents itself to the void.
Expanding upon the mechanics of the 5E Barbarian class, this PDF allows you to create occultist barbarians who embrace the influence of wayward ghosts during their rages.