The ruthless vow Lin Mu made in that underground chamber was no impulse.
In truth, after months of intense combat and his own relentless day-and-night tempering, he had spent more than enough time grinding at the peak of Rank 1.
He could feel it clearly — the barrier of his Aperture walls, once unyielding and absolute, had begun to show the faintest signs of give.
The breakthrough could be initiated at any moment.
No point in waiting. In a game board crawling with monsters and bristling with hidden dangers, every day closer to Rank 2 was another measure of insurance on his life.
The urgency left no room for hesitation.
The following morning.
Lin Mu deliberately put on his Deacon's uniform and checked in at the External Affairs Hall as usual.
Then, with complete naturalness, he submitted a one-week leave request to the hall's administrator.
The stated reason was airtight and beyond reproach: "Repeated combat during the Grand Competition has aggravated old injuries, requiring closed-door recuperation; additionally, time is needed to study and internalize Young Master Lin Feng's reward, in hopes of further advancement."
This was the advantage of authority and backing.
Unlike Fang Yuan in the original story — who, when pushing for Rank 2, had been hounded by the clan's upper echelon and forced to hide and break through in the wilderness with his nerves constantly on edge — Lin Mu was now the newly appointed Deacon of the External Affairs Hall with real power in hand, and the entire stockade knew him as Lin Feng's foremost confidant.
When he asked for leave, no one dared refuse. When he said he was entering closed-door cultivation, it was not only reasonable but expected.
From Lin Feng's perspective, a subordinate who knew when to advance and when to step back — who chose to shut himself away and train harder rather than compete for the spotlight — was the very model of a loyal and sensible man.
Without any friction whatsoever, Lin Mu carved out an entire week of absolute, uninterrupted isolation.
Back at the private courtyard in the Silent Stone District.
He dismissed Lin Ping, giving him a week's leave as well, then laid down the highest-grade warning Gu formations around the perimeter of the yard.
After that, he descended into the thick-walled, well-concealed underground chamber.
To eliminate any possibility of interruption, he even dragged an enormous boulder to the entrance and sealed the chamber's only passage shut from the inside.
Physical isolation. Foolproof.
With all of that done, Lin Mu walked to the center of the chamber.
He drew a slow breath and turned his wrist.
"Crash——!"
Accompanied by a clear, bright, almost musical cascade of sound, a full thousand Primeval Stones — crystalline, uniform, gleaming — poured from his pack like a waterfall.
Dense, natural primeval energy flooded the small chamber in an instant, condensing into faint wisps of white mist visible to the naked eye.
One thousand Primeval Stones piled up around Lin Mu's body in a small mountain that shimmered with an almost irresistible light.
This was the foundation that gave him the confidence to attempt Rank 2 right now.
Every stone had been scraped together through information asymmetry, through running the odds, through every underhanded scheme he had run since arriving in this world.
Cultivation, at its core, is a contest of resources.
Lin Mu looked at the ring of stone mountains surrounding him, his eyes carrying absolute certainty.
With enough Primeval Stones behind you, even a pig could be pushed to the heavens. And my aptitude is no ordinary Grade B.
He sat cross-legged at the center of the pile, closed his eyes, and sank his consciousness into his Aperture.
The assault began.
Inside the Aperture, thanks to his freakish pseudo-Grade-A aptitude, Lin Mu's Primeval Essence reserves far exceeded what any normal Gu Master at his rank could hold.
Purified by the Liquor Worm, that already vast sea of dark-green peak-stage Primeval Essence now filled eight or nine tenths of the Aperture's interior — a deep, viscous, coiled ocean, dense with latent force.
Break.
At the silent command in his mind, the still ocean erupted.
"BOOM!"
The dark-green Primeval Essence surged into a towering wave and crashed against the tough white membrane lining the outer walls of the Aperture — a wave that carried the force of a collapsing mountain.
"Ngh—!"
The impact sent waves of splitting, tearing pain radiating through him, as though something was trying to rip his soul apart.
The Aperture was a Gu Master's very foundation. Assaulting its walls was like cutting flesh with a blunt blade — one mistake and the Aperture would shatter, taking its owner with it.
But Lin Mu sat in the center of the stone pile, his expression cold as iron, not a single crease forming on his brow.
One wave had barely receded before the next rose higher.
The dark-green tide crashed against the white membrane again and again, relentless and escalating.
This was a war of attrition.
For a Gu Master of ordinary Grade C or even Grade B aptitude, this kind of sustained, violent assault would drain their Primeval Essence dry within half an hour, leaving them too exhausted to continue — the breakthrough failed, the body spent.
But Lin Mu's reserves were simply too deep.
His Primeval Essence supply was vast. Whenever the level inside the Aperture showed the faintest sign of dropping, he didn't even need to open his eyes — he simply reached out and grabbed two more stones from the pile beside him.
Both hands clenched. He drew them dry.
Crack. Crack.
The sound of fracturing stone filled the chamber in a steady rhythm.
Those crystalline Primeval Stones — each one brimming with pure natural essence — lost their luster the moment Lin Mu drained them.
They crumbled to grey-white powder at a visible rate, sifting through his fingers and piling up around his feet.
One stone. Ten. Fifty. One hundred.
This extravagant, almost ruinous tactic of flooding the Aperture with raw resources would have made even the well-funded core disciples of Black Blood Stockade wince and hiss through their teeth.
Lin Mu didn't care.
Money could be earned again. A dead man had nothing.
Fed by the unbroken stream of Primeval Stones, the dark-green essence inside his Aperture seemed inexhaustible, maintaining its most violent and relentless assault without pause — giving the Aperture membrane no chance to recover, no moment to breathe.
Time lost its edges.
When the sun rose over Black Blood Stockade for the second time, Lin Mu's breakthrough had reached its critical juncture.
By then, roughly three hundred Primeval Stones had been consumed. The grey-white powder around his feet had risen past his ankles.
"Crack..."
A sound — faint, yet somehow as clear as a bell — resonated from deep within his Aperture.
The white membrane, thick and solid, the boundary that had defined his Rank 1 existence — it finally gave way beneath the endless, merciless assault.
A hairline fracture appeared.
A dam of a thousand li collapses from a single ant's tunnel.
Now. Shatter.
Lin Mu's eyes snapped open. Light blazed from them. He drove the last massive surge of accumulated Primeval Essence into that crack like a battering ram.
"CRACK!"
A sharp, crystalline sound rang out from within his body.
The membrane that had confined him for so long buckled, fractured, and collapsed entirely.
Countless crystalline shards fell like a brief snowstorm, raining down into the shallow dark-green sea below, sending up tiny ripples where they landed.
Then, in the span of a single breath, those shards dissolved into points of white light and vanished completely into the Aperture.
The old gives way. The new takes its place.
Where the old membrane had been, a new white membrane formed — one that expanded the entire interior of the Aperture to more than double its former size.
This was the Rank 2 membrane.
The color had not changed much — it still radiated white light — but the purity of that light, the toughness of that membrane, outshone the Rank 1 membrane by an order of magnitude.
The realm had advanced.
And more stirring still — at the very bottom of the newly formed Aperture.
A thread of Primeval Essence unlike the dark-green of Rank 1 was slowly taking shape at the center of the essence sea.
It carried a metallic quality and a faint heat — a pale, reddish hue. It wound itself gradually through the remnants of the dark-green sea, conspicuous and unmistakable, carrying a weight and dignity that the old essence had never possessed.
This was the mark of an initial-stage Rank 2 Gu Master.
Red Iron Primeval Essence.
Lin Mu drew a long, slow breath.
He felt the transformed power within him — scarce in quantity for now, but in quality, it crushed his former peak Rank 1 essence without contest.
The corner of his mouth curved upward in a smile of cold, unrestrained satisfaction.
"Rank 2."
"Done."