Evolution

While Billy learned the technique, his control wasn't perfect and his lack of experience while staying in that state made him gather energy very slowly. It was a pity, but Billy couldn't speed up the process by using Blood Manipulation. He probably could use Acceleration Manipulation, but that made the technique imperfect.

Chi helped Billy recover health and stamina faster, and Blood Manipulation increased his reaction speed without relying on a shit ton of mana, and Rage increased pretty much all of his physical parameters alongside Body Enhancement.

"As expected, I trained a lot more with my magic, so doing this is kind of hard," Billy said when he broke his focus. "Or perhaps the innate skills made our bodies more magically oriented."