Charles Mavis was a living legend in the medicine industry. His contributions surpassed that of the current head of the Department of Medicine, Chester Cornfield.
Before he came here, he only thought that there was a severe sickness that he has to heal using his medical knowledge.
He had never imagined learning another Secret Art that even came from a junior of his clan. He diligently learns the Art and realized that this can never be attempted to anyone other than Wallace who had made ample preparations for this.
As a matter of fact, the prisoners that were sent here never managed to complete the operation due to their weak life force.
These prisoners were already magicians and they didn't even last for an hour of operation.
The last one who managed to survive was only because Charles didn't intend to pursue it further. At most, he just made use of his soul and spirit to practice on a way of handling it.