Instead of the RNG empower, or a buildup to an empower, I would like to see a more deterministic way of "empowering" abilities and spells to RES.
My proposal would be to tie this to the interrupt/concentration mechanic by adding +1 power level for each layer of concentration that your character has active. Roleplay-wise, this would reflect the idea that characters with high resolve are more focused and hit harder without spiking the character's damage output. It also incentivizes stacking concentration, which could be challenging to do in a fight given that you have other tactical considerations.
Then give a bonus to concentration generation for pumping RES in the ways described itt.