He named the Life Arcane Array that once healed him as: "Hundred Healing". It signifies the ability to cure all human diseases and to completely heal all wounds and pains in the human body.
This "Hundred Healing Formation", after years of refinement by An Jiao, has now reached a level where it can be cast effortlessly, and its power is much stronger than it was back then.
An Jiao had used it on his father more than once, trying to heal his father's scarred and battered body. But although his father no longer felt any pain, such magic could not extend the life that was nearing its end.
So, when his father An Tian was on the brink of death, although he was extremely old and his body was no longer as robust as it once was, he was free from pain. He was dying simply because his lifespan had truly reached its limit.
