Power surged inside of Yang Qi.
Before all of this started, he had the strength of a million megamammoths. But now he was absorbing the power of both the Yore-Wilds’ Heart fragment and the motherspring seed, and the particles inside of him were waking up like mad, seemingly without end, tens of thousands at a time. Each of them unleashed incomparable levels of true energy, fortifying his spatial dimensions and, in the shortest of moments, pushing him to the level of two million megamammoths. Thanks to the Yore-Wilds’ Heart, he had doubled his level of power.
Furthermore, the bright red light that shone off of the fragment contained massive amounts of preheaven yin yang power.
As a result, the yin yang seeds inside him began to fuse with the five phases power, and began to push him relentlessly toward the Yin-Yang Transformation.
If that happened, then he could finally begin seeking enlightenment of his personal domain, the God Legion Paradise.
At that point, he would be able to slaughter the Crown Prince and despise Great Sages.
“Yin-Yang Transformation, Five Phases Fusion, True Energy Cultivates Truth. Falsity is False, Truth is True, Borrow Falsity to Cultivate Truth. Gods are Tathāgatas….” 
Yang Qi’s hands moved through the air to form complex signs, each of which caused the images of countless god-spirits to enter him.
They were none other than elemental fays which represented spatial tempests, the five phases, and yin and yang. As they entered Yang Qi, they expanded his meridians, widened his spatial dimensions, and improved his capacity to contain true energy.
With that, he broke past the level of two million megamammoths.
Two million three hundred thousand. Two million five hundred thousand. Two million eight hundred thousand….
The staggering and maddening increase of power yet again caused Ghost Emperor Yama’s jaw to drop.
‘He’s already stronger than a first step Great Sage. Only, his cultivation itself is different from a Great Sage. If it weren’t for the fact that he lacks sage motes, he could definitely take on Great Sages. Once sage motes are in the picture, anyone who lacks them will lose to him, no matter how strong they are.’
Ghost-Emperor Yama shook his head. Never before in his life had he ever seen someone like Yang Qi, who, in the mere fourth Legendary transformation, had true energy that could rival a Great Sage’s. In fact, if he actually became a Great Sage, didn’t that mean he could trample the nine heavens and ten earths, and topple the three thousand realms? 
Things finally stopped with three million megamammoths, at which time his meridians pulsed with vital energy, true energy, and holy glory. As of this point, all of his energy reserves were absolutely full and couldn't absorb anything more.
The Yore-Wilds’ Heart fragment remained in his sea of energy, its brilliant red light restrained to some degree. Meanwhile, the Grand Emperor's Pagoda rotated above his head, emanating thousands of shafts of scintillating light.
It had actually benefited far more than Yang Qi just had.
‘I have the power of three million megamammoths now,’ he thought. ‘My yin yang power is at the ultimate peak, meaning that I'm just on the verge of reaching the Yin-Yang Transformation. I’ve already absorbed everything I can from the Yore-Wilds’ Heart fragment, and formed the Yore-Wilds Battle Mural in my sea of energy. Given some time, I can reach the highest level of enlightenment possible for my level. Unfortunately, there is still a tiny gap to cross!’
He was more than aware that he already had less than a hundred days to work with. Every day was important, and he needed to take advantage of every moment to achieve progress. That was the only way he could guarantee a victory over the Crown Prince.
When the time came for the decisive battle, he would show the Crown Prince and Yun Hailan who was stronger than whom. It was a moment he could hardly wait for.
After he killed the Crown Prince, he would kill Yun Hailan. Then, once he had no more enemies in the world, he could safely go to the Hanging Mountain to search for his mother. The main thing he would have to worry about at that point was the truth of his origins.
In any case, he knew that the Crown Prince and Yun Hailan would not be long-term enemies for him. They were merely obstacles on the larger path he walked, stones that he would kick aside to ensure smooth progress later on.
‘Since I'm running low on time, I’ll steal it from heaven. I need this breakthrough. The time has come for… Yin-Yang Transformation!’ Taking a breath, he drew upon the yin yang power inside of him, simultaneously splitting open the void to allow countless black and white dragons to emerge and burrow into him.
He was virtually full of yin yang power, and yet, he continued to absorb more and more. After a certain point, cracking sounds could be heard as fundamental aspects of himself began to break and then recombine.
His true energy weighed down on the yin yang power, transforming it on a fundamental level, causing the taiji symbol to explode, releasing massive amounts of vital energy.
Numerous wormholes opened up in the primal-chaos, which spat out masses of lightning; tribulation had come to suppress Yang Qi.
A huge lightning bell appeared, which settled down on top of him and sent flame lightning smashing into him. However, he destroyed it with a single fist strike. Next, a lamp appeared within the lightning, which attacked him furiously. However, he blew it out with a single breath.
After that came sabers, swords, axes, hooks, dagger-axes, spears, and all sorts of other god weapons. Each one was the type that could shake all heaven and earth, and caused the area around Yang Qi to tremble violently. However, none of them hurt him, and none lasted for longer than a single counter-attack on his part.
Millions of weapons appeared, and he destroyed them all. Next, the wormholes combined, releasing even more immense power in the form of an armor-clad figure formed from lightning.
“I am the Myriad Tribulation God!” he roared as masses of tribulation clouds rolled out around him. Without any hesitation, he reached out toward Yang Qi.
Yang Qi didn't seem worried at all. Clenching his fist, he punched out with the power of three million megamammoths, creating a stream of power that ripped the tribulation god to pieces.
More tribulations descended. There was lightning that fell like meteors, yin yang fire, dragons, and more.
However, Yang Qi had countless fist strike techniques that ensure that he defeated everything without any trouble.
In the end, heaven couldn’t do anything to him. Slowly, the space-time wormholes faded away, and the remaining aspects of tribulation transformed into vestiges of yin yang energy that streamed into Yang Qi.
Suddenly, his true energy vibrated as though it might take corporeal form. In the blink of an eye, his aura surged out into the primal-chaos vital energy, causing projections of plants, animals, and humans to appear. They were so lifelike that they actually seemed real. Yin and yang had combined perfectly with the five phases, to the point where he seemed capable of creating humans.
Of course, they weren’t actual living beings. However, they were close enough that they contained some level of intelligence, and rudimentary spirit bodies, albeit no flesh and blood.
Not even Great Sages could create actual living beings; that was something that only immortals could do, or at the very least, Demi-Immortals.
Some people actually called the Demi-Immortal level by a different name: the Ascending Immortal level.
Regardless of that, Yang Qi knew what lay next. Now that he had reached the Yin-Yang Transformation, his next step was the Personal-Domain Transformation, and the God Legion Paradise.
But what exactly did he need to do? Receive help from the legion of gods? He wasn't actually sure, and in fact, had no idea if he could succeed within less than a hundred days. All he did know was that the effort would be incomparably difficult.
And yet, he wouldn't allow that to erode his confidence, something which stemmed from the Strength of the Hell-Crushing Godmammoth.
Upon seeing the blank look in Yang Qi's eyes, Ghost Emperor Yama chuckled. “What are you stopping for, Yang Qi? Scared to keep going? Or is it too hard for you? Now that you’re in the Yin-Yang Transformation, you're not sure you can achieve that next breakthrough? You need to build up power to make each breakthrough. Now that you’ve drained your reserves, you need to work for another three years or so before you can make your next attempt. Not even the Yore-Wilds’ Heart will help. That’s an external object, and won’t help you get enlightenment. Your mind is a blank, so filling up with more energy won’t help a bit. It’s a fundamental truth of cultivation that nobody can get around.”
“Hold on a second,” Yang Qi said. “I think I just need a few more days to come up with some inspiration, and get a bit more enlightenment of heaven and earth. All my previous enlightenment has given way to power. Come on, let’s go. There’s no point in sitting around here. If those Great Sages don't find me soon, they might start causing problems in the Rich-Lush Continent.”
Rising to his feet, he vanished into the primal-chaos vital energy.
Naturally, Ghost Emperor Yama followed him.
As Yang Qi left, he committed the details of the immortal formations in the area to memory. For now, it seemed like just about everything in existence was worthy of note and contemplation, and could theoretically lead to enlightenment. A cloud. Sweet dew on a plant. A stream of water. A fountain…. Who knew where enlightenment would come from?
Before long he was back in Yanhaven.
Ghost Emperor Yama joined him, still unconvinced that he would be able to achieve another breakthrough anytime soon.
After settling down on a raised platform in his audience chamber, Yang Qi reached out and tore open a rift into the space-time in front of him. A moment later, the mercenary squad appeared. Waving his hand, he pulled over the white-robed Chaoguang.
“Mind singing that Ballad of the Dao Testimonial for me again?”
1. In a word, Tathāgatas are enlightened and transcendent beings. If you want more information check here or here. I’ll point out again that the author is tossing terms like this in for flavor purposes, and is in no way attempting to adhere to their “real” definitions.