The author still has a way out because it's apparently a dangerous technique. So, it's possible he will start damaging his body if he uses the technique too many times back to back. That being said, how broken is it, in the end? He can't land even a single hit on this girl, so it's questionable how he would fare in a real fight.
Hmm, I don't see him fighting too many people with this girl's level of critical thinking, power and analyzation skills. Honestly, for how powerful she is it seems a bit too early to be fighting someone at her level but at the same time because he's shown to simply outclass everyone else it would have gotten boring if he didn't.
3-4 chapters is a drawn-out fight thats longer than the Frieza fight huh.
And the obvious next step in defensive magic development is absorbing & gaining power from any/all incoming attacks. That's only a tiny step past what Reese is already doing (absorbing his own "compressed" attack power).
