Yuying was already an immortal before her death. It was just that the thousand years since her passing had left her weakened, so she hadn’t recovered her full powers when she first became an Envoy of Samsara.
When she’d died again in the layout, she was returned to the Tome of Life and Death. Lu Yun’s subsequent breakthrough had tapped into the power of the tome and allowed her to resurrect earlier, this time with her cultivation recovered to its peak.
Imbued with the power of immortals, Yuying was now able to manipulate the Panorama of Clarity much more easily, letting her use its core power to seal away the Tiger Prince. In addition, Lu Yun’s breakthrough had bestowed upon him a powerful death art.
This allowed him to witness all life and death within a thousand miles.
In other words, no dead folks within the area of effect could escape his eyes. He could even use the art to determine the dead’s identity, which was the most heaven-defying thing about it.
“It’s like a luopan—no, it’s even more useful!”  Lu Yun could barely contain his excitement once he understood his newly obtained death art; it would allow him to easily discover hidden tombs.
“How—how did she get here?” Qing Han blurted out. He’d been prepared to die with Lu Yun, but Yuying had arrived out of nowhere at the eleventh hour and sealed the tiger away.
“So this is where my house servant ran off to,” Lu Yun lied. “She exited in another direction at the layout of certain death. I didn’t expect her to end up in the same place as us.”
Qing Han wasn’t convinced. He’d seen Yuying disappear after cutting the arm off an undead hag and had pointed it out to the Dusk governor at the time. “But I saw—”
“The same happened with Yueshen. She was following us in Li Youcai’s body,” Lu Yun cut him off. “But when we left the layout, she was already waiting on the other side.”
“Oh, I see.” Now that he seemed to remember, Qing Han released his suspicions.
Lu Yun sighed in relief, but then a shudder ran down his spine. Wait a hot second, why do I care about his feelings? Am I——!!!
Lips trembling, color drained from his face. He recalled the glimpses of the stunning beauty back in the layout of certain death. Is that why? The layout is certainly powerful. It’s affecting me even now!
“What wouldn’t I give for that beautiful chick on my back to be real,” he muttered.
“What beautiful chick?” Qing Han lay against Lu Yun’s shoulders, his face heating up at the remark. Only he—no, she—knew that the starstone concealing her true appearance had been temporarily rendered ineffective in the layout of certain death, revealing her true self.
Did he see me? Her thoughts wandered, heart pounding.
“Hmph, the layout of certain death created the illusion of a beautiful girl. She’s fake, but she was truly the finest beauty.” Unsatiated, Lu Yun clucked his tongue. “It’d be wonderful if she were real. I’d make her mine. No, wait, that girl is actually the bony kid on my back.” Goosebumps broke out all over his body as the realization hit home.
“Put me down!” Qing Han raged when he heard Lu Yun’s whispering.
“Knock it off. If I drop you, the undead hags in the water will snatch you up.” Lu Yun unconsciously pinched Qing Han’s butt again. The envoy was so frustrated she could cry.
Yuying blockaded the coming undead hags with the Panorama of Clarity, absorbing them into the painting and burning them to ashes upon entrance. Her Emerald Mistfire was at its most powerful when deployed within the painting.
The premises were now eerily silent as the Tiger Prince’s disappearance had sent the other shadows fleeing. It would seem that the panorama was a natural bane for the living layouts.
“Feng shui and formations…. The interplay of natural landscapes gave rise to the very first layout and formation. The Panorama of Clarity encompasses natural geographical terrain like mountains and rivers, so no wonder it can contain the layouts here.” Realization dawned on Lu Yun. The painting wouldn’t be effective, if the layouts hadn’t become sentient shadows. It could seal living layouts, but not dead ones.
“Humans really are strange,” Miao commented curiously as he heard Lu Yun and Qing Han bicker. “You have feelings for the ugly eyesore on your back, so why do you deny it?”
“Shut your stinking, putrid, useless mouth!” Lu Yun flew into a rage. He had feelings for Qing Han? A fecking man? Lu Yun was damn certain that he was as straight as the straightest fecking arrow!
Feeling awkward, Miao fell silent.
“What did he say?” Qing Han asked curiously, sensing Lu Yun’s anger.
“You shut up, too!” Lu Yun twisted Qing Han’s buttocks again, making the young man grimace in pain.
“I think that for my kind, touching each other’s tail is a gesture of affection,” Miao pointed out. “The ugly eyesore doesn’t have a tail, but doesn’t it mean you like him if you keep pinching his butt?”
Lu Yun balled his hands into fists and hoisted Qing Han higher. I really can’t touch his ass again! Why does a man’s ass feel better than a woman’s, anyway? He was getting confused himself and had absolutely no idea why he was acting like this.
It has to be a lingering effect of the layout of certain death. My subconscious must still think I’m carrying a beautiful girl! He took a deep breath to drive away the intrusive thoughts. Stop thinking about ass.
Qing Han’s eyes were misty with tears and his dark face reddened, his thoughts straying to unknown places.
“Here.” Miao stopped and pointed ahead. “There’s my body.”
Lu Yun took a good look. There was an elevated road before them, wide and gently sloping upwards. At the end of it hovered a floating summit, the top of which sparkled with an unknown object.
“Have you noticed?” Qing Han asked quietly just as his ride was about to set foot on the path. “The road looks like a tongue.”
Lu Yun’s expression tightened at the observation. He quickly turned back and looked up. “So that’s how the dragon coils around the tiger!”
An enormous human face came into view above them. It spanned more than ten miles in height, its eyes widened by emotion. A large crater punctured the center of its two eyebrows, which seemed to be the cause of death.
Flanking the human face were the heads of a dragon and tiger! Both were sculpted from mountainous rock and were the same size as the giant’s skull. Most of the two beasts’ bodies were piled atop the giant, forming a bizarre arrangement.
The Duality of Dragon and Tiger!
So this was its true form. Lu Yun could also see the tiger’s eyes fixed on Yuying, a hint of murderous resentment in its eyes.
“The layout is too enormous. It won’t be easy for the tiger king to manifest and escape.” He understood the viciousness in the tiger’s eyes.
“Corpse coffin,” Qing Han remarked faintly.
“What?” Lu Yun tilted his head and looked at the envoy with his consciousness.
After a purposeful pause, Qing Han relayed an old tale. “I once read descriptions of a strange race from an ancient text retrieved from an immortal’s tomb. They existed a hundred thousand years ago, before the war of immortals. Whenever their kin died, they hunted down members of other races and used those bodies as coffins for the dead.”
Lu Yun gaped.
“You said the mountain is a large burial mound, but also that the giant body didn’t fit the proper size ratio of the dead to their final resting place,” Qing Han continued in a soft, measured tone. “If my guesses are right, the body itself is a coffin. There should’ve been a tomb housing the corpse coffin, but it was destroyed. The burial mound and the Duality of Dragon and Tiger were set up afterwards.”
“That explains everything.” Lu Yun sucked in a breath. “The burial mound and the Duality of Dragon and Tiger were probably set up by the body’s friends or family in revenge. The body wasn’t this big in the beginning, either. The grievances of the dead buried in the corpse coffin enlarged the surroundings after their tomb was replaced by a burial mound.” 
Qing Han nodded, but froze in the next second. “Look!” his voice trembled. “Doesn’t that face look like Yueshen?!”
“That—” Lu Yun’s eyes widened with shock, and he mouthed, “So the Ninefilia Specter Fostering layout was actually set up to protect and nourish her soul!”
Yueshen’s final fate in life had been to serve as a corpse coffin. Someone had downgraded the palatial tomb around her into nothing more than a pile of dirt and established the Duality of Dragon and Tiger, which provoked the dead’s grievances. That, in turn, ballooned Yueshen’s body and the burial mound, turning it into the Myriad Formation Summit that everyone knew.
The person then entered the burial mound and collected the fragments of Yueshen’s soul, setting up the Ninefilia Specter Fostering to resurrect Yueshen.
They were in a place of extreme yin and death; the extremity of anything led to its counterpart, or in this case, life.
In Lu Yun’s sect, there were records of a feng shui layout to resurrect the dead. It was said that such a layout could be found within the mausoleum of the first Qin emperor. However, the layout was dispersed in the end, so the emperor had remained dead.
“A new person must’ve entered and changed the layout again. They moved the poles of life and death away from the formation sustaining Yueshen. That’s why she became a ghost instead of coming back to life. The nine sectors and eight trigrams were originally nourishing an immortal body for Yueshen to resurrect in. However, the new person’s adjustments turned the body into a bloodcorpse, instead.” Lu Yun turned back to look ahead.
The summit floated at the highest concentration point of death energy in the mound, which meant it was also the only point of life in the mountain. This was where Miao’s body was.
2. Remember, tombs are for elites and nobility, while burial mounds are for common nobodies. Tearing down a tomb and throwing a bunch of dirt onto the coffin instead would be a huge insult to the dead.
Holy guacamole MOTHER of all reveals!! Who saw this coming? And did everyone get the sequence of events straight?
If so, fantastic. Let's not think about ass. XD
If not, let's start at the very beginning. LY realizes that the mountain is actually a huge burial mound (ch 22). A burial mound is much more humble than a tomb, it's basically a pile of dirt. A tomb is a fancy underground palace (ch 23). They bump into Yushen (ch 30), the bloodcorpse (ch 33), and realize they've been inside a huge body all along (ch 32). LY realizes that the size ratio of dead:burial mound is off (ch 38) -- the burial mound needs to be bigger to properly house the body they're walking in.
Tying it all together: Yueshen was killed so her corpse could be made into the coffin for a rando, and a tomb was built around the dead + corpse coffin. Pissed off, her friends and family destroyed the tomb, downgraded it into a burial mound to insult the rando, and set up the Duality of Dragon and Tiger for a final "up yours" so the rando would never be at peace.
They also lovingly set up a resurrection layout to bring Yueshen's soul back to life, and set up a formation (ch 33) to create a new body for her. However, another rando came in and messed up the resurrection layout, turning her into a ghost and the new body into the bloodcorpse.
Clear as mud? :D