The Yin-Yang Sanding Disc did indeed have the perfect solution to the demonic spirit problem.
Because the demonic spirit shared the same origin as Fang Xing, it had become difficult to resolve—even the Serene Ice Jade could only suppress it. If someone were to try to forcibly resolve the issue, there was a chance the process could heavily damage Fang Xing's True Spirit. From there, he would be considered fortunate if all that happened was having his foundation destroyed and completely losing all of his cultivation levels; if his True Spirit was scattered away like ash in the wind instead, it would be as though he himself had been killed and his path of Dao would cease to be.
This skill the old Wanluo gave him explored a different path, however; rather than trying to suppress or resolve the demonic spirit, it instead tried to use it to the owner's advantage. The power of the demonic spirit was of the Yin property, whereas Fang Xing's True Spirit was of the opposing Yang property. Utilizing the demonic spirit to one's advantage involved combining the two so the Yin and Yang would complement and restrain one another, allowing them to display great and unpredictable power.
In the depths of the Wanluo Court, Fang Xing sat inside a formation the old Wanluo had personally created. Bronze lanterns were placed around Fang Xing with flames like large torches while the old Wanluo stood outside and looked at him with a somber expression. "Are you certain?"
Fang Xing nodded, his face filled with resolution. "I am!"
Wanluo sighed. "Don't say I didn't remind you. This skill really is…."
Fang Xing sighed as well. "You've already said it hundreds of times already…."
Initially speechless, Wanluo suddenly declared, "Then let's start!" With a wave of his hand, he activated the formation while Fang Xing closed his eyes.
Within his Sea of Knowledge, Fang Xing stood in the air and sent a sharp gaze at his foundation. His foundation within the Sea of Knowledge had its roots buried into the earth while its top aimed for the heavens, standing as the origin of the Sea of Knowledge and the genesis of cultivation. Yet there seemed to be a dark smoke seeping out from beneath it, making the foundation seem closer to a seal put in place to suppress something powerful.
Fang Xing looked beneath the foundation and saw the very same demonic spirit that had worried him for a long time. "You want to come out?"
The demonic spirit had been formed from the portion of True Spirit Xiao Shanhe had cursed, and the its power increased alongside Fang Xing's cultivation level. During the moment Fang Xing was forming his foundation, it had been drawn in by the tribulation to corrupt it. After growing stronger and stronger over time, it was now many times more powerful than when it'd first appeared and was like a sharp sword poised to strike.
It was all thanks to the seal put in place by Qing-Yun Sect Master Chen Xuanhua as well as the Serene Ice Jade from the Melodic Ice Palace that Fang Xing was able to suppress it up until now. If it weren't for these two things, Fang Xing would have likely fallen into an incurable state by now after the demonic spirit became active.
Fang Xing was quiet for a moment, until his gaze suddenly hardened and he released a loud yell. His True Spirit attached itself to the foundation tower, and the foundation tower actually began to tilt slightly to release the demonic spirit sealed below….
ROAR
A maddened roar was released and a muddled black shadow—akin to an ancient, million-year-old demon—suddenly rushed up into the air of the Sea of Knowledge along with a large puff of black smoke. A monster with three heads and six arms could be vaguely seen within the smoke, and as the demonic spirit yawned and relaxed its body, the black smoke immediately moved to cover the Sea of Knowledge in its entirety with a power seemingly ten times greater than that of Fang Xing's True Spirit.
BOOM
The demonic spirit didn't say a word—it didn't have the intelligence to do so. Although its origin was the same as Fang Xing's True Spirit, it was created from a curse and its sole purpose was to take over the body and soul of its original owner, destroying the origin. When it was released from its seal, it paused in mid-air before exposing its great malice and rushing towards Fang Xing while its terrifying aura covered the Sea of Knowledge and threatened calamity.
"You are my biggest hidden threat, but today, your little grandpa is going to turn you into his biggest helper…." Fang Xing released a loud growl before rushing right at the demonic spirit above.
Rumble rumble rumble….
Fang Xing's True Spirit contained eye-blinding golden flames alongside hints of purple, making it appear rather solemn and sacred. As he collided with this black smoke, a maddened power immediately filled up the Sea of Knowledge.
"Blch…."
On the outside, Fang Xing's expression shifted as he spat out a mouthful of fresh blood. At such a critical moment where his True Spirit was fighting against the demonic spirit inside the Sea of Knowledge, he experienced something akin to a Qi deviation and his internal meridians were wounded.
Wanluo's expression was incredibly serious. He'd long ago prepared a dull red pellet for this specific reason, and now he placed it in a pellet pot before drawing out the pellet's medicinal properties and pushing it into the formation. With nervous eyes twinkling with light, he utilized the medicinal properties to help mend and solidify Fang Xing's body inside the formation. "Do your best to endure this, boy. If you are able to pass this, you will have taken the first and most important step forward…."
Inside Fang Xing's Sea of Knowledge, Fang Xing hadn't activated the True Samadhi Fire in his battle with the demonic spirit and had relied only on the raw strength of his True Spirit. In order to learn the Yin-Yang Sanding Disc and completely resolve this hidden threat from the demonic spirit, he could only rely on his own raw power to forcibly suppress the demonic spirit. From there, he could follow the methods the old Wanluo had taught him to instill the seal of his True Spirit into the demonic spirit's body.
If he managed to succeed, it would temper this demonic spirit into something like a second incarnation, allowing him to utilize its powers for himself. Then, by using his power and the demonic spirit's in tandem, he'd be able to master the Yin-Yang Sanding Disc skill, giving him access to an unimaginable amount of power.
The reason he couldn't use the Court of Enlightenment for this was because his aim this time was to tame the demonic spirit for himself rather than suppressing or resolving it. He needed to release this demonic spirit's power, but the Serene Ice Jade within the Court of Enlightenment would suppress it and reduce its power to a miniscule amount. This would have actually made it more difficult for Fang Xing to instill his seal.
This was the most difficult and most important step.
The demonic spirit's original purpose was to devour its owner, so its strength was naturally greater than its origin and the malice contained within it also countered the power of Fang Xing's True Spirit. Put simply, the chance of his True Spirit suppressing the demonic spirit was nearly zero, just like how a mouse wouldn't have any chance of eating an entire cat. Yet right now, Fang Xing had become that mouse who would dare to try eat a cat, revealing sharp fangs while fighting against this damned feline.
He gradually fell into a disadvantageous position with heavy wounds, and his True Spirit began to grow dim as its power diminished at an incredibly fast rate. Not only was his True Spirit being countered by the demonic spirit, but the conflict further out along his Sea of Knowledge was affecting him as well. Any damage his Sea of Knowledge received would be passed on to his True Spirit, making it weaker by the moment. The demonic spirit, on the other hand, would devour the True Spirit's power to use for itself, making it grow stronger and stronger….
In the outside world, thirteen of the nineteen bronze lanterns had been extinguished. These bronze lanterns were all connected to his True Spirit and they'd all go out once his True Spirit was completely subjugated. If such a thing came to pass, it meant Fang Xing's attempt had failed completely, his body would die, and his path of Dao would be extinguished.
Poof poof poof….
Three more lanterns went out, and the old Wanluo's expression became filled with even greater concern. "Is he going to fail?" he muttered to himself with quivering lips. He was even more nervous than Fang Xing himself—if Fang Xing failed, it would mean his theory had failed as well.
This had been a skill he didn't have a chance to test back in the past. By now, after various improvements, it had actually become much more powerful than it once was, while also becoming more complicated. When he passed it on to Fang Xing, he'd been viewing Fang Xing as his past self and wanted to utilize the boy to test out whether some of his theory had been correct. He also wanted to see just how powerful this skill could be once Fang Xing had mastered it, but it ended in failure, it meant he himself had failed as well. Fang Xing's failure was the same as the failure of his theory.
The fundamental theory behind this skill was that "men" can win over "demons".
A True Spirit was the manifestation of a person's intellect and rationality—it was a person in the purest sense. As for the demonic spirit, it had lost its intelligence and been reduced to mania, deviancy, and bloodthirst, turning it into a demon. Demons were naturally more powerful than men, yet Wanluo still believed men were able to win over demons.
"Don't disappoint me, child…."
Another lantern was extinguished beside Fang Xing. Wanluo's gaze grew heavier and he began to yell—to pray, even—from the bottom of his heart!
"I won't lose…." Although Fang Xing was being overwhelmed completely by this demonic spirit, he actually began to viciously laugh and clench his teeth. "The old bastard Wanluo said your powers will always suppress mine and that my power will never be able to match yours….
"He said that, in front of you, I'm like a mouse who'd just run into a cat….
"But I don't believe it. I—your grandpa—was born to be a tiger! A little kitty like you, do you really think you can win over me?
"Your power is dead, but as for mine… even I don't know how powerful I'll be when I become truly powerful…."
After completing his yell, Fang Xing released a loud growl. In this kind of situation where he was so thoroughly disadvantaged, not only did he not bother defending, he actually put everything he had into aggressively attacking. In front of that terrifying ocean of smoke-like malice, a bright gold with a hint of purple shot forward like a sharp arrow piercing right into the center of that smoke—and that "arrow" was precisely Fang Xing's True Spirit.
Swoosh swoosh….
In the outside world, two more lanterns extinguished into smoke, startling the old Wanluo nearby. After a few moments, another mouthful of fresh blood began to leak from Fang Xing's mouth.
"Have we lost?" Wanluo muttered to himself.
Meanwhile, within the Sea of Knowledge, Fang Xing's True Spirit mumbled to itself, "Have we won?"