It took Kane a solid two days of continuous effort to grasp the technique of channeling his entire mana into Magic Reinforcement. The potential benefit was the ability to enhance his skill. However, there was a catch. The process wasn't very efficient. In simpler terms, putting more mana into it didn't lead to a corresponding increase in attack power or duration. Kane couldn't help but wish for a system where investing more mana would directly translate into more substantial improvements.
Naturally, that was only his wishful thinking, it was clear that the system was there only to cause problems to him and use his soul like a tool, nothing else. After pulling that off, Eduns told him to focus all of his mana inside him and cover his bones with it. That was the trick to increasing his endurance.
"Even if it can't be turned into a skill, can't this be improved with use too?" Kane asked.