"Thud!" "Thud!" "Thud..." Listening to the now-calmed rhythm of the drums, Nie Kong gradually sank into a state of profound, mystical contemplation.

In a trance, Nie Kong felt as if he had merged with the colossal aura enveloping his body. Immediately afterward, his consciousness flowed out of his physical form, ascending along that aura until it burst through the hall and shot straight into the heavens.

It felt like the snap of a finger, yet also like ten thousand years had passed...

Nie Kong finally sensed the shroud of death energy hanging over Battle God Mountain, covering an area spanning tens of thousands of meters—it was overwhelming, boundless.

"Just seeing this layer of death energy, I can tell that compared to that tiny Fubo Mountain, the Battle Clan's Underworld Source is truly countless times more potent!"

Nie Kong couldn't help but marvel inwardly. However, what surprised him was that the tremendous, soul-shaking aura appearing with the seventy-third drum beat originated from the death energy above Battle God Mountain.

"This death energy comes from the 'Underworld Source'; does the drum sound also originate from the 'Underworld Source'?"

As he pondered, Nie Kong's spirit followed the aura and merged into the layer of death energy.

The next instant, Nie Kong discovered that his range of perception began radiating outwards at a terrifyingly extreme speed. In that moment, Nie Kong felt like a nouveau riche; the sudden surge in perceptive ability made him dizzy and his thoughts muddled, nearly causing the consciousness within his Second Incarnation to faint.

Fortunately, it wasn't long before Nie Kong adapted to the expansion of his perceptual range.

In less than a minute, Nie Kong's senses had completely covered the layer of death energy suspended in the void. The rapidly expanding perception filled Nie Kong with exhilaration; he looked around curiously, like a child with a new toy.

"Huh?"

Suddenly, Nie Kong felt a flicker of surprise. At the center of the death energy layer, the aura fluctuated violently, and directly below it corresponded to the peak of Battle God Mountain, from which boundless death energy continuously surged, instantly merging into the death energy layer.

Is the Battle Clan's 'Underworld Source' down there?

In a flash, Nie Kong indeed detected a huge, pitch-black opening at the summit of Battle God Mountain. However, the connecting link between the "Underworld Source" and the death energy layer was not the pillar of inky black light seen at Fubo Mountain, but was entirely transparent.

It seems that the more advanced the 'Underworld Source,' the more thoroughly the bond condensed from death energy integrates with the void. At the peak of Battle God Mountain, beyond sensing the fluctuations in the aura, the naked eye should see nothing unusual.

"I wonder what the 'Underworld Source' actually looks like?"

Nie Kong felt an urge stirring within him and instinctively focused all his attention there. A moment later, Nie Kong's perception followed that invisible, intangible bond, constantly extending down toward the dark opening below.

The deeper he went, the clearer the perception became. Gradually, a vague outline formed within Nie Kong's senses.

"That is..."

Nie Kong became even more puzzled and continued to move closer downward. The 'Underworld Source' opening was originally circular, but as he penetrated deeper into the mountain's core, its shape began to become irregular, now bearing a resemblance to the character for "Ten" ($\text{}$) from his previous life.

After a moment more, the outline of the black hole gradually sharpened, but what surprised Nie Kong was that its shape began to transform from "Ten" ($\text{}$) into the character for "Great" ($\text{}$).

"Great?"

Muttering the character in his mind, Nie Kong suddenly noticed a faint, blood-red gleam flashing in the darkness below. This discovery greatly piqued his curiosity, and the speed of his downward exploration nearly doubled.

As time passed, the red light grew brighter and brighter. After about a minute, the red radiance almost filled the entire cavern.

The pitch blackness completely vanished, and the mysterious veil that had long concealed the bottom of the cave was finally lifted. However, upon fully "seeing" the scene at the bottom, Nie Kong was greatly startled, and his downward probing instantly halted.

What lay beneath was...

A man!

It was a sturdy man, appearing to be about thirty years old, with an incomparably powerful physique, reaching a staggering height of several tens of meters!

Although the Battle Clan's Zhan Tianlun was immensely imposing, he was only a little over two meters tall. Compared to the giant lying at the bottom of the cavern, he was like a mere speck. In Nie Kong's memory, perhaps only the "Heaven and Earth Dharma Body" manifested after achieving mastery of the "Heaven and Earth Great Law" at the Heaven and Earth Sect could rival the size of this man below.

The stalwart was currently clad in a crimson robe, lying still like a statue. A blood-red luminescence radiated from the broad robe, filling the entire bottom of the cavern. The red light Nie Kong had seen earlier originated from this very robe.

Most incredibly, vast quantities of death energy were surging forth ceaselessly from the robust man's body, billowing and churning upward.

"I didn't expect a person to be at the bottom of the cavern!"

After a long while, Nie Kong managed to suppress the astonishment surging in his chest and observed the massive figure below. "The source of the death energy is the 'Underworld Source'... Could the Battle Clan's 'Underworld Source' be him? I wonder if he is dead or alive?"

"..."

Suddenly, a faint voice sounded.

Nie Kong stiffened, thinking he had misperceived, but immediately afterward, the voice came again, now vaguely discernible: "Come..."

"Come... come..."

The voice grew clearer, yet remained ethereal and unstable, like a wisp of a wandering soul escaping from the underworld, continuously drifting back and forth in his consciousness. Nie Kong's heart skipped a beat; those repeated calls were emanating from within the stout man.

He isn't dead?

Nie Kong instantly felt the urge to retreat. It wasn't fear, but because the place was truly bizarre. Since this person could be the Battle Clan's "Underworld Source," judging by the aura present when the final drum beat sounded, it was clear that no matter whether the man was alive or dead, his power level absolutely surpassed human imagination. He was here in the Battle Clan to cultivate; there was no need to jeopardize his safety and training just to satisfy a momentary curiosity by investigating the Battle Clan's secrets.

In the next instant, Nie Kong’s consciousness began to retreat out of the cavern.

"Come... come..."

Seemingly sensing Nie Kong's intentions, the emotion contained within the voice began to change, becoming somewhat anxious. Discovering this, Nie Kong had even less desire to linger, increasing the speed of his departure.

"Come..."

The call transformed into a roar, and intense fury spread outward; the death energy in the cavern surged violently like a raging tempest.

Regardless of how the surrounding death energy shifted, Nie Kong surged upward without the slightest pause. The red light below grew fainter and fainter.

"Come! Come..."

The roaring faded as it became thinner. When Nie Kong burst out of the shadowy cavern, he could no longer hear any sound emanating from the bottom. Following the transparent tether, Nie Kong's spirit returned to the layer of death energy suspended thousands of feet high in the sky.

When the words "Come" carried emotion turned to anger, Nie Kong distinctly felt a powerful pulling force emanating from the stout man's body. Yet, for some unknown reason, that force had no effect on him whatsoever.

As a result, Nie Kong departed the cavern unimpeded.

"Just a false alarm!"

Nie Kong let out a long breath.

"Thud!"

The drum sound remained gentle, but Nie Kong's spirit seemed to be driven by an irresistible force, retreating toward the Battle Sound Hall like a tide. In the blink of an eye, Nie Kong's consciousness was completely returned to his Second Incarnation...

...

"Eighty!"

Zhan Yunlan had quietly departed long ago, leaving only Zhan Tianlun and Zhan Tianyou in the hall. Their fists were involuntarily clenched tightly, their eyes wide as bronze bells, staring unblinkingly at Nie Kong. A slight sheen of sweat beaded on their foreheads; they were extremely tense, as if they themselves were the ones enduring the "Heart Drum Battle Sound" trial instead of Nie Kong.

Zhan Tianyou gritted his teeth: "Only one beat left!"

"He will make it through," Zhan Tianlun nodded heavily.

Eighty beats versus eighty-one beats—only one drum note separated them, yet the nature was entirely different. After all, only by listening to eighty-one drum beats would the "Heart Drum Battle Sound" trial be considered perfectly fulfilled, and Nie Kong would become the second Battle Clan disciple in history to have listened to the complete "Heart Drum Battle Sound," and he was an external disciple at that!

As the two waited silently, time slipped away.

"Thud!"

Finally, the immense aura covering Nie Kong fluctuated violently. The sound they had eagerly awaited rang out in their hearts.

"Eighty-one!"

Two joyful cries erupted simultaneously.

The moment the cries faded, Zhan Tianlun and Zhan Tianyou felt a sense of profound relief, their bodies feeling almost weak. But as the worry in their minds vanished, feeling the lingering echoes drifting in their hearts, an unparalleled comfort surged through their chests...

...

"Boom!"

Almost at the instant the drum sound rang out, a massive roar erupted within Nie Kong's body, and a feeling of sudden breakthrough washed over his core. At this moment, Nie Kong abruptly realized that the consciousness of his main body had awakened precisely at this instant.

However, he was immediately stunned by the changes within his body: under the continuous stimulation of the eighty-one drum beats, all impurities had been purged. All the bones in his body had become extraordinarily translucent, resembling lengths of dark jade, possessing a crystalline texture. Especially the marrow within, which was inky black, flowing and surging through the transparent bones as if it were blood moving through vessels.

Even stranger, Nie Kong discovered that the death energy he had cultivated had completely merged with the bone marrow. As a result, the purity of the death energy had increased by at least twofold compared to before listening to the eighty-one drum beats.

At this point, Nie Kong's main body's cultivation level naturally broke through from the peak of the Third Order to the Fourth Order. But the effect of the death energy merging with the bone marrow did not stop there; greater effects would manifest subtly in the future.

"Fourth Order..."

After a few seconds, Nie Kong murmured inwardly, yet felt quite speechless.

By now, Nie Kong realized he was drifting further and further away from being a normal human. First, there was that little fellow residing in his Yaochi Acupoint... then, the number of Spiritual God Acupoints kept changing... next, his blood turned an inky green due to the emergence of Spiritual Treasure Essence Qi... and now, even his bones and bone marrow had become so bizarre...

He wondered what other strange changes might occur in the future?

After a very long time, Nie Kong finally composed himself, only to suddenly notice that after such a long period, the drum sounds had not appeared... Based on his prior experience, the next thing should have been the ninth beat of the tenth round of drums!

Now, Nie Kong held no thought of resisting these drum sounds; rather, he hoped they would come more and more often.

"Has the Battle Clan's trial ended?"

Several minutes later, the drum sounds still had not arrived, and Nie Kong muttered in confusion. He instantly opened his eyes, and two faces filled with concerned expressions first came into view: one belonging to Zhan Tianlun, and the other, completely unfamiliar.

Upon seeing Nie Kong awaken, excitement flickered across both faces.

"Brother Zhan?"

Having accompanied Zhan Tianlun for eight days, Nie Kong had never seen him look like this, and he called out in surprise.

"Brother Nie Kong, this is Elder Zhan Tianyou from the Battle Sound Hall!"

Zhan Tianlun quickly introduced Zhan Tianyou, then slapped Nie Kong heavily on the shoulder before sitting down cross-legged opposite him, chuckling, "Brother Nie Kong, you are truly incredible! You actually endured the 'Nine-Nine Battle Sounds'! Back in my day, your big brother here only managed to hold out until the sixth round, and I didn't even finish all the 'Six-Nine Battle Sounds'..."

"'Nine-Nine Battle Sounds'? 'Six-Nine Battle Sounds'?"

Hearing these unfamiliar names roll off Zhan Tianlun's tongue, Nie Kong became even more bewildered. He could guess that "Battle Sound" referred to those drum beats, but what did "Nine-Nine Battle Sounds" and "Six-Nine Battle Sounds" mean?

"Oh, I forgot to tell you," seeing Nie Kong’s blank expression, Zhan Tianlun smacked his forehead. "Thousands of years ago, through the efforts of generations of Battle Clan ancestors, they finally created this 'Heart Drum Battle Sound.' Uh, I don't know how they created it. After the 'Heart Drum Battle Sound' appeared, every Battle Clan disciple had to enter this Battle Sound Hall, first to assess their cultivation potential, and second to temper their bodies. These sounds come in nine beats per round, totaling nine rounds. In our Battle Clan, the vast majority can only last until before the 'Six-Nine Battle Sounds.' Only two people have ever surpassed the sixth round, and you are the second! Likewise, only two people have ever listened to the complete Battle Sounds, and you are the second..."

"The second?"

Nie Kong suddenly understood, inwardly delighted. Judging by Zhan Tianlun's words, since the "Heart Drum Battle Sound" was established in the Battle Clan, only two people had reached his level. By the Battle Clan's standards, didn't his cultivation potential far exceed that of most native Battle Clan members? He wondered what kind of treatment he would receive in the clan in the future?

Since he was an external disciple, his treatment might not be as good as that of the preceding descendant who shared the family name, but it should be better than those who only lasted until the "Six-Nine Battle Sounds," right? However, after the initial joy, a faint worry surfaced in Nie Kong's heart. Had his performance just now been a bit too conspicuous? His cultivation talent, displayed as an external disciple, actually far surpassed that of the majority of the Zhan Clan members. If this aroused killing intent in them, it would be counterproductive.

Still, there shouldn't be any need to worry about that for now; otherwise, he would have sensed some indication from the expressions of Zhan Tianlun and Zhan Tianyou.

Seeing Zhan Tianlun excitedly babbling, Zhan Tianyou quickly reminded him, "Alright, Tianlun, it’s more important to discuss the main business."

"Right! Right! I almost forgot!"

Zhan Tianlun instantly snapped back to awareness, his expression turning serious. "Brother Nie Kong, after leaving this 'Battle Sound Hall,' you absolutely must not tell anyone that you heard the complete 'Heart Drum Battle Sound.' You can only say that you endured up to the 'Six-Nine Battle Sounds' round!"

"Uh?"

Nie Kong blinked in surprise, not expecting that the Brother Zhan he worried about showing off too much would immediately offer a solution...