Gaon, despite losing all of his magic circles upon experiencing age regression (not time regression), quickly becomes stronger than he previously was in his prime within the span of less than 100 chapters, and at the point of reading (chapter 130 currently) is already unrivalled on the continent. It's to the point that you start rooting for his enemies, because of how easily he steamrolls everything in his path to the point of it being utterly predictable and boring.

The only beings that could possibly rival him at this point are dragons, but by the time they appear in the story I imagine he will already be strong enough to effortlessly curbstomp them as well, like he has done with every other obstacle up to this point.