Cao Yun stayed silent after Emperor Weide's question. Immediately, he wanted to rebuke him & prove him wrong. However, he knew that this wasn't that easy. Of course, he could have spewed out a few platitudes, but they would have sounded hollow. They were.
After all, Cao Yun had already been forced to make tough decisions. Back in the Desolate Sepulcher, he had to both ignore the suffering of slaves and literally team up with a slaver. Of course, he did it with the hope of helping more people. In the end, he had succeeded. However, he couldn't look away from the innocent people who had suffered because of him. The world was a messy place. No one had absolute answers. As much as Cao Yun wanted to prove that Emperor Weide was evil, he could see in his eyes that he genuinely believed in his words. Emperor Weide wasn't trying to deceive himself. He knew that his acts had been horrible, but he had weighed them against an even worse fate and had made a choice.
Try as he might, Cao Yun couldn't find the right words. After all, only actions could prove one's truth in such a difficult matter. Unfortunately, Cao Yun was terrified that Emperor Weide was right. In the end, even the soul fragment of Emperor Nuwa had pushed Cao Huiying toward her own sacrifice in order to save Cao Yun and make him strong enough to protect the Hongchen Kingdom. Full of doubts, Cao Yun decided to simply ignore this conversation.
Politics in the Desolate Sepulcher had been absolutely awful for him. Apparently, it wasn't limited to the Desolate Sepulcher. Honestly, Cao Yun didn't want to face such situations. With his cultivation, he could have forced Emperor Weide to make him his successor. However, he had chosen Huang Cixi. The ultimate reason was that Cao Yun didn't want to be tied down to the Hongchen Kingdom. Even now, he was thinking about leaving to explore the universe and study the deepest secrets of the Dao everywhere.
There were other reasons, though. One of them was that he didn't want to have to make those choices again. Cao Yun could decide what was right and wrong for himself, but he had realized that making those choices for countless others was above him.
He had been too weak to protect the slaves of the Desolate Sepulcher without manipulations, just like Emperor Weide had felt too weak to oppose Empyrean Asura without sacrificing the Shui family and the Cao family. In the end, Cao Yun came to the same conclusion. He needed to be stronger if he wanted to forge his own path. Weakness would force him into insurmountable decisions. Then there wouldn't be any good answers, only bad ones. And Cao Yun was tired of choosing the lesser of two evils. Unfortunately, he was also painfully aware that it might happen again. Unless he completely withdrew from the mundane world and lived as a hermit, he would have to make those decisions. So he had to be strong enough to be able to impose his own solutions.
The more Cao Yun thought about it, the more he realized that he was deluding himself. Of course, he would face incredible forces and inescapable dilemmas. After all, he had seen extraordinarily powerful cultivators in Axiu Qian and Cleansed Asura's memories. Against those, he was a mere fly. They could literally eradicate the Piaolu planet in an instant if they wished to do so. All that simply reminded Cao Yun how insignificant he was, how insignificant everything around him was. He had not even lived for a century, a little more than a quarter of that, actually, shy of a third.
Suddenly, Cao Yun felt the intense desire to cultivate. But, for now, he had to deal with Emperor Weide. Since he hadn't fully recovered, Cao Yun still needed time to rest before applying the perfect seal he had in mind to his enemy. That didn't mean that he couldn't use any other seal in the meantime.
"Yong Weichen, I will apply a seal of death in your sea of consciousness. At any given moment, I can trigger it and cause you to die in abject agony. Will you oppose me?"
Although Cao Yun was a 1st-grade Exalted Demon, he wasn't that much more powerful now. After all, he was still weak from his breakthrough, and Emperor Weide was extremely powerful. If Emperor Weide wanted to resist, it could be a terrifying fight. However, Emperor Weide was honest. He had decided that Cao Yun was the best chance for mankind, so he submitted to his Dao Heart oath. If he tried to break his oath, this would damage his Dao Heart and probably cause inner demons to form. In the worst-case scenario, it might actually kill him. That being said, Dao Heart oaths had already been broken historically. Only a handful of those who had broken them didn't encounter terrible fates, though.
Emperor Weide let Cao Yun put this seal of death in him. As a matter of fact, it was a modified version of the Slavery Brand. Cao Yun had Dian Mo help him. They spent almost ten hours crafting this seal. With his better understanding of the Dao of Death, Cao Yun was slightly better than Dian Mo when it came to creating this specific seal. The two of them together made a seal that Emperor Weide had no chance of ever unraveling. If Cao Yun so desired, he could inflict untold pain on his enemy. Besides, he could kill him at any moment now. Immediately, Cao Yun had the temptation of doing so, but he restrained himself.
For those ten hours, Emperor Weide was in pain. Cao Yun made sure that he had visions of the past. He used his own memories with Death Energy to increase the negative emotions. Emperor Weide felt as though he was literally living the slaughter of the Cao family. He also felt the anguish and despair, as well as the physical pain of many victims of the demonic cultivators and his own men. After all, Emperor Weide was responsible for everything the demonic cultivators had done since he had armed Demon King Mo Wang. Without Emperor Weide's use of Demon King Mo Wang, he would never have been able to gain so much power that he had actually threatened the Hongchen Kingdom.
Honestly, Demon King Mo Wang was Emperor Weide's real regret. He had thought he could control him better than that. However, Demon King Mo Wang had broken free of his control and had shaken the entire Hongchen Kingdom. Without this terrible mistake, the Hongchen Kingdom would have fared better against the demons. In the end, it wouldn't have changed much to the current results, to be fair. Still, this mistake plagued Emperor Weide, and Cao Yun pushed on it as much as he could.
In the end, the seal was complete. Both men were exhausted. Before retreating into a chamber to rest, Cao Yun exchanged some more words with Emperor Weide.
"Since the Imperial City is in ruins, all the people will be evacuated to nearby cities. You, however, will go with my companions and me. We will go to Baziyun City."
Baziyun City was the capital of the Wu Province, to the west of the Imperial City. As such, it was farther from the Sunmen Province and the Subei Province where the war against the demons raged. This was the stronghold of the Huang family and the ancestral home of the Cao family. Obviously, Emperor Weide was shocked. He was convinced that Cao Yun would do everything to send him on the front lines in order to oppose the Empyrean Asura Theocracy. Before Emperor Weide could retort, Cao Yun answered his thoughts.
"Empyrean Asura can strike anywhere now that our defenses have fallen. We won't be able to wage war on the borders since we can't protect them all. If we tried, we would simply stretch ourselves too thin. However, our strength has always been our unity. Thanks to your lies, we'll be able to protect our unity. To ensure victory, we must destroy theirs. I've been to the demon territory, their kingdoms are not unified, they're simply all terrified of Empyrean Asura. His recent failure will already have weakened his hold on them. I am certain that civil unrest is spreading throughout the Empyrean Asura Theocracy. In fact, a few regions have most likely broken away from the Empyrean Asura Theocracy.
"If we simply kill Empyrean Asura, not only will the demons fall back into civil war and chaos, but they will fear us as well. With the spread of the Sutra Faith and the Sisters of the Abyss preaching the words of the Weaver of Souls once the war is over, most demons won't dare attack us while we rebuild our defenses. I can assure you that merely getting rid of the head will work. However, it would be better for us if the Silver Wolf Marshal stayed alive. I believe he would be instrumental in stabilizing the demon kingdoms. Chaos can be good to us, but only up to a certain point, after all."
Cao Yun's words made sense to Emperor Weide. The young man had been close to the demons for a very long time. Behind his words, Emperor Weide could tell that he knew much more than what he was saying. Of course, Cao Yun didn't explain that he was quite literally the hand behind the curtains, using the Sisters of the Abyss as his puppets. The worst threat for mankind was the faith in the Demon God Da Mo, so mankind would support both the Sisters of the Abyss and the Sutra Faith. Honestly, Cao Yun could begin to see a far future in which humans and demons wouldn't hate each other as much. Even if they couldn't live together, they didn't have to hate one another to the point of wishing extinction upon the other.
"Unfortunately, cutting off the head of the monster isn't as easy as you make it out to be. Even with your cultivation, this won't be enough..."
Emperor Weide hesitated before mentioning it, but, in the end, he did.
"Your Soul Embryo is damaged. Although you have the strength of a 1st-grade Exalted Demon, it's still relatively weak. Your Soul Embryo will probably take a century to recover, and you can't push it too far, or it might shatter and collapse. Of all the 9th-grade Spirit Warriors, only I am young enough to actually be useful on the battlefield. Sect Leader Xuan is impressive, I admit, but he's really too old now. Even if Sect Leader Xuan, Matriarch Huang, and I face Empyrean Asura, I do not think that we can win. Your help could tip the scales. But even then, I am still unsure. It depends on how damaged his soul actually is. Besides, we would need to go through many more powerful demons to get to him..."
Unfortunately, Cao Yun had to acknowledge all the words of Emperor Weide. That being said, there were other ways.
"We won't have to go to him. Fighting him on his territory would indeed put us at an incredible disadvantage. If we want to beat him, we have to stack all the chances on our side. Instead of coming to him, we'll make him come to us. I know exactly how to bring him precisely where I want. You shouldn't worry about that. Moreover, this is the one place where we might have a chance of crushing him. And I'm not talking about his body, I'm literally talking about his Demon Soul.
"On this matter, I want you to tell me everything that you know about his Demon Soul. You know who he actually is, after all. And I guess that you know more than that."
For a few seconds, Emperor Weide was silent. He didn't ask for more details about Cao Yun's plan. The determination in his eyes was enough. From now on, Emperor Weide could no longer change course. He had gambled the fate of the Hongchen Kingdom on Cao Yun, and he would follow through. To be fair, without Cao Yun, he was certain of their defeat and extermination. With him, he simply thought that there was an actual chance of survival, and he would take it.
"Everything you want to know is in the private library of Emperor Nuwa. This is where I learned everything I needed to know. Although only emperors are allowed to read those precious texts, I will let you consult them."
The Hongchen Kingdom and the School of Ren Dao stressed the importance of knowledge. Every human had to have access to knowledge in order to help all of humanity grow stronger and wiser. However, they also acknowledged the importance of secrecy in other matters. Even some families decided to hide their martial arts or cultivation techniques so that others couldn't know their weaknesses. As such, it didn't surprise Cao Yun that many documents were kept extremely secret.
From his spatial ring, Emperor Weide took out a small bamboo slip. It was wrapped up and didn't seem impressive at all. However, there was a strong aura around it, the aura of Emperor Nuwa. Just being in front of it caused Cao Yun to feel something. He had an intense desire to kneel in front of the bamboo slip. Thankfully, he controlled himself and took it. Instinctively, he sent his spiritual senses inside. In an instant, he was in a gigantic library. Or rather, the gigantic library was in him.
Indeed, from his sea of consciousness, enormous stone and wooden steles emerged from the infinite ocean. All those steles were engraved with various texts in various languages. They formed a library as vast as the Everlasting Earth Palace. A mortal wouldn't have enough time in one lifetime to read all those texts. In fact, Cao Yun even saw languages he was unfamiliar with. They came from very small texts with many missing pieces. Most likely, those were records from the Legendary Era. Even in Cleansed Asura's memory, those languages were unknown. They looked similar to others he had seen, but were still too different to be read by Cao Yun.
Despite his intense desire to read everything, Cao Yun decided to focus on the important information first. As a matter of fact, some of the documents were public information, but others were extremely secret or personal. Indeed, this library contained personal diaries and political reports, among other things.
Emperor Weide guided Cao Yun to one stele in particular, 'Record of the Last Great Crusade'.