How about this change to Defiance?

What if when you use Defiance, instead of just generating the extra HP that you'd have to heal back up or regen back up, it's just there (kinda how Thrill of Battle works) and while Defiance is inactive, it gives 25% extra healing? Like say for Titan's table flipping and Tumult, you get topped off, use Defiance, get hit by Mountain Buster, Infuriate, Berserk, Inner Beast, turn off Defiance and bam almost full HP again (I don't crunch numbers yet) but the difference is you don't have to worry about getting healed back up the next time you hit Defiance.

I like that option.