Gu Daoyi was experienced and knowledgeable, and this had primarily come from his first lifetime. In the subsequent eight lifetimes, he had spent his time working hard on cultivation in the Immortal Realm. Additionally, there was nothing much in the Immortal Realm worthy of his notice, and his 10th lifetime had just begun.
In the Celestial Realm, it was not uncommon to use one's self as a formation. Some people had walked the path of strengthening their physique, and were thus capable of inscribing a killing formation in their body, and some were the descendants of supreme Immortal Beasts, and had thus been born with sturdy Godly bones—they did not need to cultivate, and were naturally capable of inscribing a killing formation in their bodies.
Yet he had definitely never seen one that could actually inscribe not just one killing formation in their body.
A maniac like that actually existed? Such a freakish achievement was actually possible?