I’ve seen this theme play out a few different ways. Sometimes the failure is a magical burnout—like they lost their power entirely and have to reinvent their craft from scratch, maybe using forgotten or forbidden techniques. Other times, it's a public disgrace; they were a prodigy who collapsed under pressure and now has to claw back respect in a cutthroat magical society. The transformation usually isn’t just about getting stronger. It’s about a shift in perspective. They stop relying on raw talent or textbook spells and start understanding magic on a deeper, almost intuitive level, often by blending disciplines everyone else thought were useless or incompatible.
A great example is Quentin from 'The Magicians', though his failures are more existential. He thought magic would make him happy, and when it didn't, he had to completely redefine his relationship to his power and his purpose. The destiny change feels earned because it’s paired with massive personal cost—he’s not the same person who started. The magic system itself often reflects this: their new abilities might be rougher, less polished, but far more adaptable and real. It’s less about transforming destiny into something grand and more about forging a destiny that’s genuinely theirs, flaws and all.