According to the records on Devil Heart Dao, the most critical part of this secret art consisted of accumulating sufficiently powerful Yin Devil Will. The stronger and greater the Yin Devil Will, the more powerful the eventually formed Devil Heart. That, in turn, meant that the body could control more Prime Devil Energy.
Which translated into more power.
'Let's continue. I've only expended slightly more than ten units of Mental Energy.' Lu Sheng quietened his heart and continued upgrading Devil Heart Dao.
Grand Elder had once mentioned that any cultivator of Devil Heart Dao who could form three Devil Will hearts and eventually give birth to a Devil Heart would already have met the average standard in the past.
Which meant to say that the disciples who had mastered Level Three of Devil Heart Dao used to be the core disciples of the sect in the past. Their strength could reach the pinnacle of Four-Vein Level.
This was a cultivation route that took a lot of time. In the lineage of Phantom Listening Skill in Prime Devil Sect, those who could form five Devil Will hearts were considered talented.
As for seven or eight Devil Will hearts, they were the top-notch elites who were guaranteed to enter the realm of Snake.
To be honest, the cultivation of Devil Heart Dao did not do much to help raise one's strength. Rather, it focused on gathering and accumulating Devil Will, forming reserves of it in one's body. All these accumulation would pay off explosively when one forms the Devil Heart.
But none of these were a problem for Lu Sheng.
Soon, after expending a dozen units of Mental Energy, the third Devil Will heart formed.
Lu Sheng had previously absorbed way too much Prime Devil Qi. Hence, it was a piece of cake for him now. His physical body was leaps and bounds stronger than that of others. In turn, this enabled him to store up way more Prime Devil Qi in his body than others.
Lu Sheng could sense that these three Devil Will hearts were intimately connected to him. They felt like three actual hearts that grew outside of his body. Large volumes of Prime Devil Qi were being channeled from his body into these three hearts through some mysterious method. Moreover, these three hearts were also absorbing Devil Qi from around them into themselves.
'... I've still got plenty of Mental Energy. Continue.'
This was the time to accumulate power. Naturally, Lu Sheng was generous with his investment.
Quickly, he threw a dozen units of Mental Energy out again and the fourth Devil Will heart soon appeared.
Followed closely by the fifth.
The sixth...
The seventh...
The eighth...
The ninth...
In one sitting, Lu Sheng gave birth to all nine Devil Will hearts. Eight of them in heart form, and one human-faced snake encircling him, levitating in midair.
'If seven or eight Devil Will hearts indicated that one was a genius guaranteed to enter the Snake realm, I wonder how far I can go now that I've upgraded directly to the highest achievement of nine hearts.'
He glanced at the remaining Mental Energy. Few units of it were left. The rest had been expended in one go.
A heavy fatigue washed over him. Lu Sheng understood that this was caused by him producing too many Devil Will hearts in one go.
Even if his body was incredibly powerful, he could barely take the compressed load which others spent many years of cultivation experiencing.
'Eight Devil Will hearts. The typical incubation period is twenty four hours. In other words, a day.
After that, I can generate the ultimate Devil Heart. That's when I would have fully mastered Devil Heart Dao. Devil Heart Dao is the foundation of everything. The subsequent Phantom Listening Skill is merely an application technique. It's actually even easier.
Now, it's time to head back and get some good rest as I wait for it to complete.' Lu Sheng sucked in a deep breath of air and dragged his weary body along. Lightly, he leapt out of the cave and dashed towards the Prime Devil Sect's library.
All his Mental Energy had been thoroughly consumed. Within such a short period of time, he had already reached his limit in attaining this level. Thereafter, he would have to wait and see how powerful was his Devil Heart.
Lu Sheng understood that he had already arrived at the most powerful state possible in the Prime Devil Sect's Phantom Listening Skill lineage with the help of the Modifier. He was already at Level Nine of Devil Heart Dao, which was perhaps merely the theoretical extrapolation of others in the past.
One had to understand that once the Devil Heart had been formed, there was no going back. However many Devil Will hearts one produced in the past, that was the number he had to live with for the rest of his life.
In turn, the formation of these Devil Will hearts depended on the volume of Prime Devil Qi one had absorbed and purified via Phantom Path Mantra previously.
With sufficient Prime Devil Qi, one would produce more Devil Will hearts. If Prime Devil Qi was lacking, naturally the Devil Will hearts would be reduced both quantitatively and qualitatively.
Lu Sheng remembered that he had once read from a historical record of the Prime Devil Sect that the ancestor of the lineage of Phantom Listening had once formed eight Devil Will hearts in a short period of time. The result was that he was ranked as one of the top three experts in the entire Prime Devil Sect at that time.
That was the Prime Devil Sect at its peak. Snake realm experts had been common among its ranks. Moreover, because of its good connections with some Noble Families, the territory it held sway over had rivaled that of some smaller Noble Families.
In terms of physical strength, Lu Sheng was confident that he far surpassed others. In that case, these nine Devil Will hearts would certainly exceed expectations in their power; undoubtedly, they would attain the pinnacle of the Phantom Listening Skill.
***
Central Plains, the White Bell City.
"Here, here!"
"Senior Apprentice Brother Yan Kai! I'm here!"
Yan Kai dragged his lethargic body out of the inn, yawning. He was about to head to Xu Family's Buns nearby for breakfast when he heard a lady's voice shouting at him from a short distance away.
With widened eyes, he gazed in the direction of the voice.
Amidst the throng of people, a petite girl in a white dress was waving vigorously at him and shouting out loud, "Senior Apprentice Brother Yan Kai!!! I'm here!! Over here!" The girl's face looked babyish; clearly, she was young. Probably around twenty years old, although she could pass off for a girl in her tens. She was also only half the height of most adults.
Presently, she hopped up and down in the midst of the crowd, trying hard to draw Yan Kai's attention.
"Little Qin?" Yan Kai paused in surprise, recognizing her as his master's new youngest disciple, accepted recently.
As a core disciple from his mountain, Yan Kai was considered one of the few who finished last. Had it not been for the similar bloodline that ran through his veins, and had it not been for the rarity of this bloodline, whether or not he could even enter the sect would have been in question.
"It's me, it's me!" Little Qin chirped as she shoved her way through the crowd unceremoniously. Before long, she made her way to Yan Kai.
Only now did Yan Kai notice another girl behind his junior apprentice sister.
This girl was dressed in a scarlet dress, with a scarlet umbrella in her hand. Her hair was raven-black and a cherry lip decorated her pretty face. She was a rare beauty.
"Senior Apprentice Brother, let me introduce my friend Yingying. She's a good sister of mine whom I've just met in the White Bell City!" Little Qin introduced her to Yan Kai with all smiles.
"You're Little Qin's Senior Apprentice Brother? Interesting... you're here to take part in the Hundred Lineages Meeting too?" Umbrella girl Yingying—more accurately, Hongfang Bai—was sizing up Yan Kai from top to toe with a high-and-mighty look.
Ever since Lu Sheng had joined one of the sects, she had been bored stiff and hence started occupying Yingying's body to sneak out. She had been to Central Plains in the past, but not to the White Bell City. Times were different now; many years had passed. All the elders from the Hundred Lineages who had hunted her were now dead or in seclusion. Once she realized that, her fears faded and she began to act without inhibition.
Anyway, apart from Lu Sheng, she had never been afraid of anyone in the world.
"Are you participating in the Hundred Lineages Meeting too, young lady? This lowly man is Yan Kai. I'm not thinking of participating, but my teacher is understaffed and so has summoned me back as a helper."
"It's the Hundred Lineages Meeting... we should show up even if just for the sake of exposure," Little Qin interrupted. "Besides, Wan Shun Palace's Young Master Bai Xiu's out of solitary confinement now and should be attending the Meeting too. Aiya... really... it's..."
Little Qin managed to blush and look love-stricken at the same time.
"Sigh..." At one glance, Yan Kai could tell that his junior apprentice sister was love-stricken again.
Wan Shun Palace was one of the major sects in the upper three grades. Ranked third in the Hundred Lineages, it was a mighty faction. Within it, Young Master Bai Xiu was reputed to be next-in-line to become the sect master, having inherited the sect's unique title for the first seat—Heaven's Appointed.
Heaven's Appointed Bai Xiu—one of the three most powerful first seats in the Hundred Lineages. He had long since been a Snake realm expert and enjoyed unparalleled limelight.
"The Meeting's beginning in a few days. Junior Apprentice Sister, how's teacher? Is he in good health?" Yan Kai interrupted her.
"He's alright. You'll see for yourself, Senior Apprentice Brother. But he often goes on and on about the promise you made back then and complains that you've put too heavy a burden on yourself," Little Qin whispered. "But he'll definitely come before the Meeting. When he does, you just have to see him yourself."
Thoughts of the past came to Yan Kai. He fell into silence and a complicated look appeared on his face.
"Okay, okay, let's go shopping! I haven't been in the White Bell City for such a long time. The Meeting's going to take place nearby so we might as well stay here and tour the place," Little Qin suggested.
"Alright..." Yan Kai could only chuckle helplessly. This time, he had come on his own and so could go anywhere he wanted.
"How about Young Miss Yingying?" Yan Kai looked at umbrella girl. Facing this young lady who hailed from an unknown background, he could not help but feel a heavy pressure emanating from her, leaving him with an uncomfortable sense of danger.
"Alright, I like shopping too. No harm taking a look—"
"Yingying."
Before Hongfang Bai could finish, she was cut off by a deep male voice.
Immediately, her carefree expression turned gloomy and overcast. She turned her head and looked at the other side of the street.
God-knows-when, a group of people had appeared opposite the three of them. The one who walked in front was a man with a stoic face and slender figure. A heavy aura and pressure emanated off him. It was Lu Sheng, who had only just come out of the sect.
"Done playing?" He stared at umbrella girl.
Hongfang Bai, who had been in a cheery mood just a moment ago, was completely in a foul mood now. She humphed coldly and walked over obediently.
"I got to get back now. Have fun."
"Yingying..." Little Qin wanted to tug at her sleeve, but was immediately held back by Yan Kai.
"Don't go over..." His face was solemn and grave. Glancing at the Prime Devil Sect logo on the corner of Lu Sheng's robes, beads of perspiration broke out on his forehead.
Little Qin turned around and was immediately stunned by her senior apprentice brother's horror. She could only watch as umbrella girl Yingying followed Lu Sheng's company till they disappeared in the crowd.
Only then did Little Qin pull away from Yan Kai's large hand.
"Senior Apprentice Brother, what's wrong? Were those Yingying's family?"
"The Prime Devil Sect... to think that he's here in the Central Plains as well... and he's even joined the Hundred Lineages under the Prime Devil Sect..." Yan Kai mumbled softly to himself.
Lu Sheng—the right-hand man of the big shot in Shangyang Family, Shangyang Jiiuli. His cultivation was unfathomably deep and profound. He ruled the Northern Lands as the overlord of Crimson Whale Sect.
Most importantly, this man had left him traumatized and extremely terrified.
If not for the Unlaughing Master episode, perhaps Yan Kai might even think that he could make friends with Lu Sheng. But since that incident, both Wan Hezi and himself had truly come to realize Lu Sheng's true form in that test.
In that test, the simulation had modeled the gatekeeper after Lu Sheng, since he was the strongest person in the area at that time. "Lu Sheng" had given them the lesson of a lifetime, and they had paid for it with their blood.
...Until they finally exited the infinite-loop illusion. Even so, they had been psychologically scarred. It was a trauma that could never be erased.