Although this meant that Brian Cooper could not easily use his original power, it brought far greater benefits than other methods. By contracting his demonic energy, he could prevent his cultivation in the immortal path from being disturbed by his own demonic cultivation, making his power purer. Once the cultivation was complete, Brian Cooper's immortal power could reach the highest level, allowing him to stand shoulder to shoulder with any powerful figure of the demon realm or holy immortal spirit. His strength would immediately leap to a higher level, not much inferior to his original demonic cultivation.

After completing this step, Brian Cooper's body became completely empty, with a fist-sized mass of dense black energy inside him—this was the culmination of Brian Cooper's lifetime of cultivation. It had already been sealed by himself, and at this moment, Brian Cooper was at his weakest in all of his seven thousand eight hundred and sixty-nine years of life. Even an ordinary human could easily defeat him at this moment.

Silently reciting the incantation for the Jade-Skin Immortal Body recorded in the "Heavenly Mansion Purple Galingale," Brian Cooper began to transform his own body.

If this were a beginner cultivator, this step would be extremely difficult. Although there were many practitioners, very few had the perseverance, fortune, and aptitude to reach the higher levels of cultivation. Moreover, the Jade-Skin Immortal Body that Brian Cooper was cultivating was the most profound method of the Daoist sect, requiring extremely high attainment to even begin. Ordinary people could not reach this step. After all, Brian Cooper already had years of cultivation experience, his body had been tempered, and his spiritual will was far beyond that of a beginner, so he found it easy to start and progressed rapidly.

Cultivating the Jade-Skin Immortal Body meant merging the vital energy of heaven and earth with the physical body, with the ultimate goal of refining one's flesh into an indestructible existence, the body itself possessing infinite power. This step was the most time-consuming, but it was not difficult for Brian Cooper.

After absorbing enough vital energy of heaven and earth, he would transform his body again. After each transformation, he could absorb even more vital energy, repeating the process until the end.

The purpose of cultivation is to become immortal, and the highest, twelfth level of the Jade-Skin Immortal Body requires breaking through this final barrier to complete the ultimate cultivation and achieve an indestructible divine immortal body. Therefore, Brian Cooper inevitably had to face the tribulation that one must undergo to become immortal. This was the most difficult part—one careless mistake would not only waste all previous efforts, but if he went astray, even Brian Cooper's original attainment could be lost.

This ordeal was similar in effect to the demonic tribulation that Brian Cooper had undergone in his demonic cultivation. Even though Brian Cooper was prepared and had already been tempered once, it had only been a few dozen days since he had achieved demonic cultivation, so it was still extremely difficult to handle.

First came all kinds of illusions, endless changes, and extreme temptations, followed by water, fire, wind, and thunder in succession, bringing indescribable pain. Even though he knew these were manifestations of his own mind, Brian Cooper still almost couldn't endure it several times. If he had given up at this critical moment, it would have been tantamount to seeking death, so he had no choice but to grit his teeth and hold on.

Fortunately, Brian Cooper had already been through tribulations. Although the process was different, his will had long been tempered to be incomparably firm. After enduring hardships, Brian Cooper finally broke through to the final stage.

The last stage of the Jade-Skin Immortal Body was the tempering by heavenly fire. As soon as the pure fire of the heavenly realm entered his body, it was like a magnet attracting iron, heading straight for the mass of demonic energy condensed in Brian Cooper's body to burn it. Brian Cooper cried out, desperately resisting. Only then did he realize that the pure fire of the heavenly realm was inherently incompatible with the demonic energy in his body, and its power was unmatched. If he couldn't resolve it, his painstaking cultivation of seven or eight thousand years might be destroyed in an instant.

Brian Cooper couldn't care about anything else. With a single incantation, the Twelve Banner Gate Escape transformed and shifted. Brian Cooper withdrew the Two-Yi Microdust Array into his body to wrap around his true essence. Under the protection of the Two-Yi Microdust Array—one of the seven most profound Daoist arrays—the pure fire of the heavenly realm lost its target and began to temper Brian Cooper's body instead.

"That was close." Brian Cooper finally breathed a sigh of relief. He realized he was courting death—cultivating such a profound immortal path, enduring so much suffering, and he hadn't expected it to be incompatible with his own cultivation. If he hadn't happened to have the Twelve Banner Gate Escape at hand, he would have lost at least several hundred years of attainment.

Although the tempering of the body by the pure fire of the heavenly realm was painful and hard to endure, this stage was not as dangerous as the previous one. The seven-colored heavenly fire burned fiercely, tempering Brian Cooper's body. Brian Cooper could withstand it, and having passed this great ordeal, he couldn't help but feel relieved.

The pure fire of the heavenly realm continuously entered from the top of his head, refining his entire body from head to toe, from the outside in, tempering his muscles, bones, organs, blood vessels, and skin.

Originally, after the tempering by the pure fire of the heavenly realm, it would dissipate on its own. However, during the tempering, a trace of purple flame energy remaining in Brian Cooper's body unexpectedly grew stronger and fused with the pure fire of the heavenly realm, beginning to absorb each other. In fact, the Purple Clear Doushuai Fire, the highest state of the purple flame energy, and the pure fire of the heavenly realm share the same origin, so they naturally attract each other.

This unexpected situation startled Brian Cooper. If the heavenly fire remained in his body, unless he never used demonic power again, the pure fire of the heavenly realm could backfire at any time. Moreover, he would lose a protective treasure for no reason—the Two-Yi Microdust Array of the Twelve Banner Gate Escape could no longer be withdrawn and would have to be used to guard his primordial spirit. Also, his demonic power could not be used for the time being, lest it provoke the heavenly fire.