When it came to refining the Metal Rend Leaf Gu — the Rank 2 Gu born from his Vital Gu — Lin Mu could not afford even a sliver of carelessness.
He did not immediately force his Primeval Essence into the two Gu worms.
After all, the more supreme the blade being forged, the colder the water needed to temper it.
Before the true trial of refinement, any trace of excitement, anticipation, or fear would stir ripples through the sea of his mind — and those ripples would translate into the smallest fluctuation in Primeval Essence output.
In Metal Path Gu refinement, even a fluctuation lasting one ten-thousandth of a breath meant total destruction.
Exhale... Inhale...
Lin Mu sat cross-legged on the cold stone slab and slowly closed his eyes.
Like a monk entering deep meditation, he began long, measured breathing.
He peeled away every fantasy and every fear from his emotional core — layer by layer, ruthlessly, like stripping an onion.
Half two hours later.
When Lin Mu opened his eyes again, those dark pupils held no trace of any intense human emotion.
What remained was the absolute stillness of a thousand-year-old well — deep, dead-silent, radiating a rationality that bordered on the inhuman.
Mental state: reset.
He extended both hands.
In the air before him, to the left floated the Rank 1 Vital Iron Leaf Gu — bound to his life, connected by blood, and utterly docile in this moment.
To the right floated the Rank 1 Metal Rend Gu, emanating a faint metallic sheen and exhaling a bone-piercing sharpness.
Directly below the two Gu worms, a small pile of Morning Star Sand glittering like scattered stars, along with over a hundred crystalline Primeval Stones, had been arranged in the most convenient positions.
Everything was ready.
"Rise."
Lin Mu's mind stirred.
The shallow-red Red Iron Primeval Essence at the base of his Aperture flowed outward as gently as spring rain, forming two soft yet irresistible halos of light that enveloped both Gu worms simultaneously.
The refinement began in earnest.
With a full week of trial-and-error behind him, Lin Mu's opening was steady as a mountain.
But the true challenge had only just arrived.
As his Vital Gu, the Iron Leaf Gu on the left held a natural affinity for Lin Mu's Primeval Essence.
It cooperated without resistance, opening its will completely — even actively reaching out to embrace and accommodate what was coming.
The Metal Rend Gu on the right was another matter entirely.
This exceptional Gu worm had been refined and subdued by Lin Mu, but it was not his Vital Gu.
The moment it sensed another will attempting to merge with it — to erase its original form — its Metal Path nature was ignited in full.
Clang——!
The Metal Rend Gu thrashed violently within the Primeval Essence halo, resisting the fusion with frenzied intensity. Ripples spread across the surface of Lin Mu's light halo.
Lin Mu's gaze remained still as a dead pool.
In that moment, he split his consciousness into two with formidable force, displaying a level of micro-control that was nothing short of breathtaking.
The left half of his mind moved like a gentle spring breeze — continuously soothing and guiding the Iron Leaf Gu's will, keeping it in the most perfect state of receptivity.
The right half slammed the Red Iron Primeval Essence output upward on that side, suppressing the Metal Rend Gu's rebellion like a heavy iron hammer — pressing its will, beat by beat, into alignment with the Iron Leaf Gu.
It was a silent, grinding tug-of-war that devoured mental energy at a terrifying rate.
In the stillness of the chamber, cold sweat broke out across Lin Mu's forehead and ran down his cheeks, dripping onto the stone floor.
Deep within his mind, a dull, needle-like ache pulsed in waves — the warning sign of mental energy being pushed to its absolute limit.
But his bloodshot eyes did not blink once.
His hands held as steady as iron ingots cast in midair, and his Primeval Essence output maintained an absolutely smooth flow that was almost unsettling to behold.
Under that terrifying suppression and mediation, the two entirely different yet same-origin Metal Path wills were finally forced together.
Hum!
The outlines of the two Gu worms blurred and merged in midair, forming a basin-sized mass of blazing white light — blindingly bright, and not entirely stable.
The light mass had taken shape.
But Lin Mu knew this was only the first gate.
Without hesitation, his free left hand became a blur.
He snatched up the Primeval Stones prepared below and began feeding them into the unstable mass of white light in steady, methodical succession.
Hiss! Hiss! Hiss!
Each stone that entered the light mass dissolved instantly — like ice dropped into boiling water — its heaven and earth essence greedily devoured by the raging Dao Marks, leaving only grey-white powder drifting downward.
As the Primeval Stones were fed in one after another, the basin-sized mass of light began to contract sharply.
Round after round, it shrank.
When the light mass contracted to the critical threshold of a large bowl's size, something changed.
Under the extreme compression of density, the two wills that had been forcibly kneaded together erupted in violent rejection once more.
The entire light mass began to shudder without pattern or rhythm.
Within the blinding white light, a dangerous crimson hue flickered — like a timed explosive on the verge of leveling the entire underground chamber.
This was the precursor to a failed refinement.
"Now!"
At that razor's edge between success and destruction, the corner of Lin Mu's eye — twitching faintly from the pain — snapped upward.
He did not panic. His mind moved, and his left hand reached down with precise, unhesitating accuracy, grasping the prepared handful of Morning Star Sand.
Without a single pause or tremor, he scattered it in a perfectly even arc into the light mass that was on the verge of going berserk.
The timing was exact to the last fraction.
Whoosh——
The moment that dull grey Morning Star Sand made contact with the light mass, it transformed — miraculously — into countless flickering points of blue starlight.
Those motes of light acted like the finest lubricant and adhesive simultaneously, seeping into every corner of the light mass in an instant.
With a touch that was both impossibly gentle and impossibly tenacious, they bonded and neutralized the two Metal Path Dao Marks that had been on the verge of tearing each other apart.
The violent shuddering of the light mass ceased in the very instant the starlight merged with it.
The savage, all-consuming fury that had threatened to destroy everything was replaced by a deeper, heavier, more refined sharpness.
"Hah..."
Lin Mu exhaled a long breath inwardly, but his hands did not stop moving.
The final contraction phase had arrived.
Steadied by the Morning Star Sand, the light mass continued its stable inward collapse — until it had shrunk to the size of a fist.
The white light at this point was blinding beyond measure, as though a miniature sun were being born in midair.
"Last one."
Lin Mu held his breath and fed the final Primeval Stone into the mass.
Hummm——
The light mass greedily swallowed that last fuel, then imploded with a sudden, violent inward contraction — reaching a state of ultimate condensation.
Then, a faint, crisp sound rang through the chamber — soft as a cocoon breaking open.
The blinding radiance receded like a tide.
A brand new Gu worm hovered silently in midair before Lin Mu's eyes.
It was no larger than half a palm. Its body was no longer the blue-black of before — it had taken on a deep gold that radiated suppressive force.
Its shape was still that of a leaf, but along every edge ran dense, natural metallic veining, fine as saw teeth.
Simply hovering there in stillness, the Rank 2 peak-grade aura it emanated — sharp enough to cut gold and shatter jade — caused the surrounding air to warp faintly.
The Rank 2 Vital Gu — the Metal Rend Leaf Gu.
"Hah..."
Lin Mu's entire body went slack like a bow finally unstrung.
He slumped back heavily against the stone wall, breathing in great, ragged gulps.
His face was paper-white from the severe drain on his mental energy — but within that pallor, his dark eyes burned as bright as cold stars in a moonless sky.
He had succeeded.
A week of trial-and-error. Hundreds of Primeval Stones reduced to ash. Countless life-and-death simulations. In this moment, all of it had borne its sweetest fruit.
"Let me see just how sharp you really are."
After resting for a short while, Lin Mu stood, unable to wait any longer.
His mind stirred, and a thread of Red Iron Primeval Essence poured from his Aperture into the Metal Rend Leaf Gu that had just settled into his palm.
"Go."
He extended two fingers like a sword blade and drew them lightly across the air toward the massive Cyan Steel Rock in the corner of the chamber — the same slab that sealed the passage, and hard as iron.
Whoosh——!
No sharp crack of splitting air. Not even a whisper of wind pressure.
A finger-length arc of deep gold light, silent as a ghost in the dark, slipped from his fingertips and vanished into the enormous Cyan Steel Rock.
No explosion. No shattered fragments flying outward.
Everything was perfectly still. Still in a way that felt almost wrong.
Lin Mu walked forward and examined the surface of the rock under the dim lamplight.
There was only a single mark — so fine that a strand of hair could not fit inside it.
Lin Mu ran his finger along it. The surface was smooth as a mirror. That was the absolute flatness left behind when supreme sharpness cleaved through matter in an instant.
But that was not the most terrifying part.
Lin Mu drew a slow breath, extended one finger, and flicked it lightly against the Cyan Steel Rock.
Thud.
With that single soft sound —
Crack. Crack. Crack. Crack...
A dense cascade of fracturing sounds erupted from within the rock.
The slab that had appeared completely intact split outward from that hairline cut at its center — countless cracks spreading in an instant like a spider's web across its entire surface.
Then, with a low, heavy crash —
That enormous rock, collapsed entirely before Lin Mu's eyes, crumbling into a pile of fine rubble and powder.
"What a domineering penetrating, armor-shattering force..."
Lin Mu stared at the stone dust blanketing the floor. A barely-suppressed fervor and awe flickered in his eyes.