Power Charge Generation must always require cull/corpse???

You made power charge generation tied to corpse/cull skills only. It's unnecessarily restrictive. As long as you can clear the endgame w/o power charge skills, people will choose to not interact with them. It's just too inconvenient.

Can you not introduce at least a new support gem?

Power Charge Generator
Effect: Supported skill does 90% less damage. Has +1 sec increased attack/cast time. Generates 1 power charge on hit with an enemy in close range.

This would be jank. But it would at least let us play with power charge skills without a Voll's chestpiece, or some frenzy=>power hack. It's unnecessarily restrictive right now. Please. Rage as a generator is fun because it's not so restrictive.

Take the time to type "charge" as a research in your skill tree, you'll see plenty of them giving access to charges, if you only want access to it through skill/support Devour is the way.