The silk book recorded not a complete cultivation method, but a series of secret techniques. Besides the "Profound Soul炼妖術 (Refining Demon Technique)", there were also several bizarre secret methods such as "Blood Burning Art" and "Soul Seizing Technique". Most of these secret techniques were demonic, not only strange but also evil. The "Human Yuan Fiend Pill" recorded within involved using the cultivator's entire body of Qi and blood as a furnace to condense a Fiend Pill. Seeing this, Zhang Ling's body and mind sank. At this moment, his Qi and blood were severely depleted, having been caused by Wei Shen using this evil method. If he hadn't escaped, he would have been sucked dry long ago. Although the "Human Yuan Fiend Pill" had a 30% chance of allowing someone to break through to the Golden Core stage, the defects of this Fiend Pill were also mentioned later. Because this external pill technique was, after all, a man-made Golden Core, once successfully refined, although one could become a Golden Core cultivator, their cultivation would be difficult to improve further. It would remain at the initial stage of the Golden Core realm. Zhang Ling roughly looked through it once and put away the damaged silk book, planning to study it carefully later when he had time. Finally, when he was sorting out other miscellaneous items, he also found two black coffins, emitting a strong Yin energy. They were also a special kind of magic tool. The two black coffins were one large and one small. The large one was more than two zhang long, and the small one was just enough to fit a human corpse. Zhang Ling opened them to take a look. The large one was empty, but the small coffin actually contained a broken corpse.

This corpse only had half of its body left, but it was a purplish-black color. He sensed a strong corpse aura on it. It was actually a corpse monster, but it was so broken that even this kind of alien creature couldn't possibly have the ability to move. Suddenly, he thought of what this person had said before, that in order to resist his sword talisman, he had wasted a corpse monster whose strength was comparable to the mid-stage of Foundation Establishment. Could it be this corpse? Looking around, Zhang Ling came to the side of the corpse bear. This corpse monster, transformed from a demon beast, was lying motionless on the ground. He scanned the corpse monster with his divine sense. The corpse bear had fallen to the ground with its back facing up, its back was a bloody mess, and wisps of black gas surrounded it. "Oh, there's still spirituality." Zhang Ling looked at the corpse bear a few times. The black gas on its body was slowly absorbing the surrounding Yin energy. This phenomenon was definitely not that of a dead object. He raised his hand and used his spiritual power to wrap the corpse bear and flip it over. Looking at the ferocious and terrifying corpse bear, Zhang Ling put the corpse bear into the large coffin. As expected, it fit perfectly. Wei Shen not only had a strong cultivation base, but also had two Foundation Establishment stage corpse monster puppets. He was probably more than capable of dealing with any late-stage Foundation Establishment cultivator. Zhang Ling laughed, put aside these distracting thoughts, and collected the things on the ground. Then he turned his attention to the ground. More than ten zhang of the ground were covered with stone slabs of various sizes, engraved with strange runes. This was the formation set up by Wei Shen, but what made him strange was that this formation was very strange, neither an attack formation nor a defense formation. Although he couldn't recognize what kind of formation it was, he also knew that such things were expensive. Zhang Ling thought for a while, then removed the formation stone slabs from the ground one by one and carefully put them into his storage bag. Finally, he came to the mutated vine and frowned as he looked at the abnormally thick vine. An hour later, Zhang Ling flew up from the underground rift with a pale face and opened up a simple cave in a small mountain not far away. Now his top priority was to stabilize his injuries. ... In the blink of an eye, three months had passed. On this day, Zhang Ling walked out of the cave with a gloomy face, sat on a gray stone, and looked at the horizon. He had been recovering from his injuries during this time. However, the injuries on his body were more serious than he had imagined. It could be said that he only had half his life left. Although the spiritual power in his dantian had completely recovered, the meridians throughout his body showed signs of atrophy, and he could only exert 70 to 80% of his strength. Moreover, the situation was still deteriorating, which was a sign of damage to his foundation. During this time, he felt fortunate that his cultivation hadn't regressed, let alone progressed. Whenever he practiced and circulated his cultivation method, blood-colored runes would appear on his left arm. Then, these blood curses would transform into wisps of black gas, filling the meridians throughout his body.

Whether he was cultivating or casting spells, this black gas would erode his body. Although the amount of black gas was small, it was a big hidden danger. Not only was his cultivation limited, but this black gas was like a maggot attached to the bone, and he could not get rid of it. During this time, he had specifically studied Wei Shen's cultivation experience, which recorded secret techniques, as well as the method of refining the Human Yuan Fiend Pill on the silk book. He guessed that this black gas might be Fiend Qi. Because the Human Yuan Fiend Pill itself was a Fiend Pill refined by fusing the human body with Yin Fiend and Yang Fiend. This black gas was transformed from Fiend Qi, and after carefully examining that cultivation experience, he had some understanding of Fiend Qi. There was no accurate definition of what Fiend Qi was. Generally speaking, as long as one killed a large number of living beings, they would have Fiend Qi on their body. This was a special kind of aura. For example, butchers in the secular world would have Fiend Qi on their bodies if they slaughtered too many pigs. Ordinary remnants of souls and fierce spirits could not enter the bodies of these people, but would be impacted by the Fiend Qi on these people. The same was true for cultivators. The more intense the killing aura, the heavier their own Fiend Qi would be. It was said that to a certain extent, it would also attract heavenly punishment and lightning tribulation. It was often more difficult for these cultivators to advance. Therefore, even demonic cultivators would not kill a large number of living beings. In addition to this introduction to Fiend Qi, some special spiritual powers in the world were also called Fiend Qi. This type of Fiend Qi was divided into Yin Fiend and Yang Fiend. Neither Yin Fiend lands nor Yang Fiend lands were good places, and they would all cause damage to the human body. The underground rift he had entered not long ago was a Yin Fiend land, and he had also been to places where Yang Fiend was rich. The Burning Flame Valley in the Falling Star Mountain Range was a Yang Fiend land. These two places were also where Wei Shen collected Yin Fiend and Yang Fiend. Among them, White Bone Yin Fire was formed by the power of Yin Fiend. And the Yang Fiend power used by this person was condensed from the poisonous fire in the Burning Flame Valley, and was stored in a special magic tool, a white jade bottle. At that time, this person was also able to easily find his cave in Falling Star City by sensing the white jade bottle. Thus, with Yin and Yang dual Fiends, plus a demon core as raw materials, he used his body as a furnace and the vines parasitic in his body as a medium to refine the Human Yuan Fiend Pill. As long as it succeeded, he would naturally die without a doubt, and the black gas in his body was the residual Fiend Qi after the White Bone Yin Fire and Burning Flame Valley poisonous fire were condensed. This was undoubtedly harmful to the human body. Now, if he wanted to eliminate the Fiend Qi in his body, Zhang Ling didn't have any good methods for a while. However, through studying the secret techniques on the silk book during this time, although these were all Yin and evil techniques, their ideas were often novel, and the principles and methods of some techniques were different from ordinary secret techniques. Among them, the "Profound Soul Refining Demon Technique" occupied most of the space. After carefully reading this secret technique, he found a way to solve the Fiend Qi problem. Although it was just his guess, it gave Zhang Ling some hope. The "Profound Soul Refining Demon Technique"