This is a high level medical ninjutsu. Similar to the Secret Healing Wound Destruction technique, this jutsu allows the user to survive any otherwise normally fatal damage and instantly heal from the damage. A unique trait of this jutsu is that it can momentarily give the user the appearance of death.
When combined with dark chakra, this jutsu can also be used to physically enhance the person to superhuman levels of speed, strength, and healing might.
Despite having little care for human life, Shinnō has demonstrated remarkable medical knowledge and prowess without the aid of chakra. With only basic medical tools, he can perform flawless surgeries to save people from near death. In addition to the human body, Shinnō has also demonstrated great knowledge of the human mind. He has repeatedly shown himself able to understand how a person thinks and exploit it to suit his needs.
In terms of ninjutsu prowess, Shinnō's skills focus more on his knowledge of chakra and human physiology. He can easily injure a person to the point of appearing dead and using a jutsu to resurrect the person, even if it is himself. He also has shown high sealing jutsu prowess as he was the one who sealed the Zero-Tailed Beast within Amaru.
With his knowledge of Dark Chakra, Shinnō was shown as able to unleash a powerful transformation to take a human being well beyond the normal limitations. By combining his special jutsu with the dark chakra, Shinnō is able to transform into a superhuman body that can freely access his chakra without hand seals or any apparent effort of chakra build-up. He is even able to unleash powerful shock waves of dark chakra and freely access all Eight Gates without any drawbacks as long as he still has access to enough dark chakra.