RPGMemes

That final element has this amazing interplay where you feel that you’re burning your humanity (or species neutral equivalent term) as you use magic, and your innate or monsterous side comes through, it was a really cool design and I’d love to see it taken even further with a subclass that also incorporated hitpoints into the flow somehow, meaning that you are a tank before you cast your spells, but literally burn out your life force as you do so, revealing the monster underneath. It could be really cool for a vampire or something else that has an interesting interplay with harm, healing and magic.

The Order of the Lycan blood hunter has a similar mechanic. Every blood hunter has abilities with a HP cost, but the lycan might also go berserk if they start the turn with less than half HP.