It took a huge amount of power to start the Engine of the One God. True, Yang Qi had picked up quite a bit of power from the Aeonic God Temple, as well as the passageway to the Primeval Age. Unfortunately, even just the initial clash with the Five Great Lokapālas was quite draining, and Yang Qi wasn’t inclined to continue that trend. Even if he completely drained himself, he didn’t think he would be able to kill them.
Instead, he would conserve as much power as possible to use on the Four Emperors of the Heavenly Court.
Thanks to Sectlord Nine Yangs, he knew that the four emperors were conniving against him with the lord of the Unrestrained Heaven. They had set up deadly spell formations in the Heaven-Dao Operation God-Temple that would prevent him from escaping into the Myriad Worlds Monarch Chart. Then, when he was stuck, eight top experts would all attack him at the same time. It would be a dangerous, tricky situation, that was for sure.
That said, he had strategies of his own to rely on.
For one thing, it seemed unlikely that the lord of the Unrestrained Heaven and his four suzerains of hell were completely in line with the Four Emperors of the Heavenly Court. They had their own goals and motivations, including the ultimate desire to take down the four emperors, gain more power in the Dao Defense League, and harvest universal fortune.
That said, universal fortune wasn’t an easy thing to seize, especially for those who followed the dao of devils. As such, Yang Qi just needed to find the right weak spot to strike at.
Back in the Sage Monarch Heaven, Yang Qi reached out to Patriarch Annalist with divine will and asked, “How is your cultivation base? Have you fully recovered?”
Patriarch Annalist was on the same level as Grand Emperor Myriadmagic Heavenspan; both of them were apex-level cultivators. He had been around since ancient times, and his enlightenment regarding daoist magic and energy arts surpassed Yang Qi’s by a significant margin.
Thankfully, Yang Qi had more experience than the average person, and had encountered much good fortune. He had absorbed the seven gods from the Aeonic God Temple, and although he had not fully assimilated all of their magic and power, he had definitely pushed his energy arts to roughly the same level as Patriarch Annalist.
Right now, he understood things far more clearly than before and had resolved all of his previous issues and areas of ignorance.
“I'm fully recovered,” Patriarch Annalist said, “and have even progressed a bit. Given some time, I’ll definitely be able to defeat Grand Emperor Myriadmagic Heavenspan in a fight.” He sighed. “There’s an old poem from the mortal world that says, each generation will produce talented individuals; their dissertations will be passed down for centuries. We outdated old-timers need to step aside for the next generation. In each new age, new elites will rise up.” 
Yang Qi shook his head. “I appreciate the kind words, but you're mistaken. Other than me, there’s no one worthy in the current generation. Leaf Dao-Denier is strong, but he doesn't come close to matching up to Grand Emperor Myriadmagic Heavenspan. And the Dao Defense League itself is the idea of the Four Emperors of the Heavenly Court. In any case, Patriarch, if you’re fully recovered, I want to take you to see someone.”
“The devil lord of the Unrestrained Heaven, Wave Wind. We're going to go to the Unrestrained Heaven and see if we can make a deal with him.”
“What? Wave Wind? Unrestrained Heaven? That place is very dangerous, and those people are working with the four emperors. It’s a place filled with so many heaven-devils that not even all the immortals working together would dare to go there. It’s definitely as dangerous as a dragon’s pool or a tiger’s den. The power of the Unrestrained Heaven is so incredible and mysterious that it can cripple the dao of immortals. Heaven-devils are almost impossible to kill, and even worse, they can be born from heart-devils or the mere will of heaven. This is going to be a very dangerous trip.”
“Don’t worry, I control the power of hell. And the Unrestrained Heaven has hellish characteristics that I can manipulate. I want to see for myself just why this Wave Wind is working in opposition to me. If he doesn’t agree to acknowledge allegiance, I’ll just destroy his Unrestrained Heaven. Dealing with monsters will be a lot easier for me than handling the Four Emperors of the Heavenly Court. After all, my energy arts are specifically designed to be the bane of hell-born fiend-devils.”
“In that case, my life is in your hands, sir. Where you go, I go.” Patriarch Annalist really didn't seem very worried, and as they flew along he actually spent most of his time pondering the mysteries of his All-Eternity Spring-Autumn Annalist God-Dao Scripture.
It was an art left behind by ancient gods, after all. If he could cultivate it to completion, he would be extremely awe-inspiring and righteous, and would have extraordinary advantages when dealing with wretch-devils.
They flew along for some time before catching sight of an area up ahead that was filled with devilish clouds and sinister winds.
“Young Sir, that's the Unrestrained Heaven right there,” Patriarch Annalist said. “It exists between the realm of hells and immortal worlds, here on the very edges of primal-chaos paleo-energy. That barrier of devilish clouds is called the Immortal-Melting Miasma, and it lives up to its name in every way. Any immortal who touches it will be melted, and ultimately transformed into a heaven-devil. It’s hard to say how many immortals have become part of the Unrestrained Heaven over the years because of that miasma. In ancient times, there were even gods who perished and became part of it.”
“Let’s head inside.” Yang Qi seemed completely unimpressed by the miasma and simply flew right into it. As he went along, nothing that lurked within even noticed him.
There were countless heaven-devils everywhere, all of whom were bizarre to say the least. Some had numerous wings, some were three-headed and six armed, and some existed in the forms of books or cauldrons. When it came to heaven-devils, sometimes the offspring didn’t resemble the parents in any way. In that respect, they were like the nine sons of the dragon. 
Because there were absolutely no restraints on such heaven-devils, and they could end up in just about any possible form, they were known as unrestrained heaven-devils. They were free and independent, unfettered and able to act in any way they wished.
One characteristic they all shared was incredible strength. They lived within the devilish miasma, sometimes fighting each other and sometimes leading armies in campaigns of war. They cultivated wretch-devil energy arts and followed the law of the jungle in every way. There was no larger society controlling things, nor was there a royal dynasty issuing orders.
The Unrestrained Heaven was definitely no smaller than the Hell of Mahānata. And truth be told, it had no official lord or ruler. It was so mysterious and unpredictable that no one knew exactly what was lurking in its deepest depths.
Wave Wind wasn’t truly the lord of the entire Unrestrained Heaven, he was just the leader of one of the most powerful and active factions. To date, no one had risen up to completely seize the legacy of the place’s essence.
It was like the Tusita Heaven, in that regard—ultimately lordless. Although the Tusita Dynasty was powerful, its emperor didn’t truly control the immortal world. Even Leaf Dao-Denier, who had passed the Essence Trial, was only partly its ruler.
As Yang Qi proceeded through the mists and past the countless battling heaven-devils, he started to understand how the Unrestrained Heaven was shaped. The portion that was visible from the outside was only the tip of the iceberg, while the rest of it stretched into primal-chaos like the roots of a tree. It almost seemed alive, twitching and wriggling as it expanded into various universes around it.
‘This place is enormous,’ Yang Qi thought. ‘Just what I would expect of a place where ancient gods died.’ As for the devilishness that was so destructive and dangerous, his Strength of the Hell-Crushing Godmammoth easily protected him from it.
That said, the place was so enormous, and filled with such power, that Yang Qi could tell he would need to reach the Deathless Heavenly Stairway before he could go very far inside.
Normally speaking, tracking down one individual here would be like fishing a needle from the sea. Thankfully, he had planned how to find Wave Wind in advance. By means of Sectlord Nine Yangs, he had managed to plant an energy art seed on him, which he could use to track him down no matter where he went.
The Unrestrained Heaven seemed like a place of endless fighting and battle, whether in the sky, on the land, or in the sea. The entire place was a battlefield. Some of the leaders of the heaven-devils had built fortifications; however, such places could easily be overrun if other, stronger heaven-devils came along.
Because of the constant influx of universal power, new heaven-devils were born with every moment that passed. As they breathed in the vital energy of the Unrestrained Heaven and used it for cultivation, they were naturally imbued with its fundamental nature. They lived for slaughter, fighting, devouring, and destruction.
Each and every heaven-devil was, by nature, vicious and bloodthirsty.
However, as they furthered their cultivation, they would develop more human characteristics, and would become more intelligent and wise. As they learned to manipulate the dao of heaven, they could seek luck and avoid calamity.
“The only rule here is that you have to kill,” Patriarch Annalist said, shaking his head. “Everywhere you look, battles are being waged. It's worse than the Hell of Suras! Even old-timers who come here will end up getting killed. Anyone who ended up besieged by these heaven-devils and suppressed by the essence of this place would have no hope of escaping. I doubt even Lesser Gods could last. There are far more hells in existence than immortal worlds, and hells are a scourge on existence. A cancer. One of these days, they’ll surely devour the many heavens in existence.”
Yang Qi nodded. “That’s exactly why the paramount Sovereign Lord created the godmammoths, to crush hells. But now the godmammoths are gone, and for some reason the hells seem much weaker than in the past. It makes you wonder why.”
1. The poem he quotes is a real-life poem by Qing Dynasty poet and historian Zhao Yi.
2. The ‘nine sons of the dragon’ are a very common aspect of Chinese mythology: info here.