Homebrew that needs to be playtested

I have been working on a collection of various homebrew subclasses, species, spells, and so forth for upcomming books that I need help playtesting from players and groups outside of my own. Below is one of the subclasses: The Path of Retribution Barbarian.

This subclass revolves around the idea of building up a vengance through taking damage to unleash deadlier strikes against your quarry.

I need playtesting from various groups, party combos, and varying levels to see if it's balanced for exisitng content. Any feedback on how to fine-tune this subclass is appreciated. Depending on the outcome of this, more content will be posted for potential playtesting along the way. Thank you in advance.

Path of Retribution