C2584 Full blood resuscitation
When a person was ill, or seriously injured, especially when he was ill to the point of death, his body would form an aura of death. However, if he could turn the aura of death into anger, then the illness would naturally be cured.
The art of reincarnation was to turn the death aura in one's body into life.
Qin Lang and Feng Canxie were both already severely injured