Once Dean opened his eyes, an explosion of light happened inside that grotto. His body got surrounded by a silver aura, looking like flames dancing around him.
There was no mistake. That energy around him was nothing but "Willpower". His new "Willpower", with a different shape, a different strength, a radical change that would never get reversed.
The boy made it, he broke through the Fourth Pillar, Refinement. The Pillar where the Ascendant's "Willpower" passed for a period of transformation that would change its properties and rise by leaps and bounds its strength. No Ascendant remained the same when they advanced to the Fourth Pillar. That was a universal rule.