Yet the joy of refining his first Rank 2 Gu worm was nowhere near enough to make Lin Mu lose his head.
He closed his eyes and felt the contrast inside his Aperture — the Earth Birth Gu radiating its dense, weighty aura against the Metal Rend Gu's biting, razor-sharp presence. The difference was stark.
"Earth Path governs inclusion and bearing. So when its will faces Primeval Essence suppression, the fusion is relatively slow and gentle — even if conflict arises, there is room to buffer it."
"But Metal Path is different. Metal Path governs slaughter. Its Dao Marks are sharper and far more exclusive than those of other paths."
Lin Mu rolled his shoulders and shifted into a more comfortable position.
"If I let this momentary success go to my head and blindly apply the 'inclusive' technique I just used for Earth Path Gu refinement to Metal Path Gu refinement..."
"The moment those two torrents of violent metal-sharp energy clash, there will be no buffer whatsoever. It won't just trigger a furnace explosion ten times worse than anything before — my Vital Gu, the Iron Leaf Gu at the core of the refinement, will be torn apart in an instant."
If his Vital Gu was destroyed, his Aperture would suffer devastating damage. Even if he survived, he would be bedridden for the better part of a year — a complete cripple.
True steadiness was not escaping danger by luck. It was having the restraint to pull back from the edge of a cliff when temptation was at its most extreme.
"Stop."
Lin Mu severed the greedy impulse stirring in his heart.
He stood, gathered the scattered materials on the stone table, and walked to the crude stone slab bed in the corner of the chamber. He lay down without even removing his outer robe.
He forced himself to think of nothing related to Gu refinement, letting deep sleep restore the mental energy he had burned through over these past days.
At the same time, in the depths of his subconscious, he began slowly stripping away the muscle memory of Earth Path refinement, clearing space for the entirely different understanding that Metal Path refinement would demand.
The following day. Noon.
When Lin Mu opened his eyes again, they had recovered their clarity. His mind and blood were back at their absolute peak.
He opened the chamber's heavy stone slab and called Lin Ping, who had been waiting outside.
"Lin Ping, make another trip to the market and the surrounding cultivator stalls."
Lin Mu handed over a heavy pouch of Primeval Stones and issued his new procurement order in an even tone.
"Don't bother with anything expensive or high-quality. I want you to buy as many of the most basic, cheapest Rank 1 Metal Path Gu worms as you can find — defective Iron Thorn Gu, Iron Block Gu, that sort of thing — along with the corresponding supplementary materials. However many there are, buy them all."
"Yes, Deacon!" Lin Ping asked nothing further, took the pouch, and hurried off.
Lin Mu understood his situation clearly.
He had no master to guide him, no clan resources funneled his way for practice. His only option was to force a path open through sheer persistence.
He would use these cheapest of Metal Path Gu worms to simulate the Dao Mark collision between the Iron Leaf Gu and the Metal Rend Gu.
Only by finding that razor-thin point of equilibrium through hundreds upon thousands of violent Metal Path explosions would he dare to lay hands on his own Vital Gu.
Half a day later, after Lin Ping had hauled basket after basket of cheap Gu worms and ore slag reeking of metal into the underground chamber, the heavy stone slab fell shut once more with a thunderous boom.
This session of closed-door cultivation was longer than the last. And far more brutal.
Time drained away in silence like sand through a glass. The chamber's stone door did not open once for an entire week.
The underground space, once thick with the smell of damp earth, had been transformed entirely.
The air was saturated with the acrid stench of scorched metal and ozone — the biting smell left behind by violent Metal Path Primeval Essence friction and detonation.
Bang!
"Damn it — can't hold it!"
Another sharp explosion rang through the chamber — but this was nothing like the dull thud of an Earth Path furnace explosion. It came with a piercing shriek of shattering metal.
In midair, a blazing mass of light collapsed in an instant, fragmenting into countless tiny, razor-edged metal shards that sprayed outward in all directions like a storm of steel rain.
Clang! Clang! Clang!
The shards — fragments of the exploded Metal Path Gu worms and supplementary materials — struck the chamber's hard blue-steel rock walls and left a dense constellation of white gouges.
Lin Mu stood at the center of the explosion.
He had activated Earth Ring Body in advance, but the rampant, out-of-control sharp energy was simply too fine and too savage.
His hands — those long, steady hands — were now covered in a dense web of cuts, shallow and deep alike. Blood dripped from his fingertips onto the stone table, staining the scattered metal debris red.
Metal Path Gu refinement was more than ten times more dangerous than Earth Path.
It was a torment that tested the practitioner's endurance and precision to the absolute limit. This was not kneading dough.
This was attempting to forcibly weld two supreme blades together while they were actively hacking at each other at full speed. The slightest lapse meant the backlash turned inward.
And yet, on Lin Mu's exhausted face, there was not a single trace of retreat. Instead, a nameless fervor had gradually taken hold.
He did not even bother bandaging the wounds on his hands. He simply stared at the table full of wreckage, sparks of comprehension flickering in his eyes.
"I understand now..."
Ignoring the stinging pain in his hands, Lin Mu picked up a fragment of shattered Iron Thorn Gu and turned it slowly between his fingers. A profound, shaking realization rose within him like a crashing wave.
"Someone who has never truly refined a Gu worm is like a frog at the bottom of a well — thinking that refinement is nothing more than following a recipe, gathering the listed materials, and kneading them together with Primeval Essence until something forms."
"But only once you've truly crossed the threshold. Only once you've felt this uncontrollable collision with your own hands. Only then do you realize the vastness of what lies within."
"Rank 1 advancing to Rank 2 — a simple fusion of basic same-attribute Gu worms — is already this dangerous, this difficult to control."
"Then what of Rank 3 advancing to Rank 4? What of Rank 5 ascending to immortality? What of those immortal Gu refinements that cross schools and fuse multiple different Dao Marks?"
"Before the boundless laws of the Refinement Path, I am not even a frog at the bottom of a well. I am a mayfly adrift on the open ocean, gazing up at a sky too high to ever reach."
Extreme suffering brought extreme clarity.
And within that clarity, Lin Mu finally understood — deeply, viscerally, even with a faint tremor of awe — just how terrifying the weight behind that name truly was.
That name which towered over an entire era in the original story. That name called the Supreme Grandmaster of the Refinement Path.
Fang Yuan.
The man who regarded all things in heaven and earth as materials, and all living beings as fuel for his furnace.
When he refined those supreme immortal Gu worms, what kind of world-ending Dao Mark collisions did he face?
Behind that effortless, almost artistic mastery — what unfathomable calculation and absolute command over the laws of heaven and earth lay concealed?
But this realization did not shatter Lin Mu's resolve.
On the contrary, in this sealed and suffocating underground room, that sense of awe became the most powerful fuel imaginable.
Fang Yuan — that supreme old demon who existed only in memory — seemed to take shape now as an invisible, formless presence. The most demanding, and the finest, teacher Lin Mu could have on this path.
Not only the Great Love Immortal Venerable. More than that — the Heaven Refining Demon Venerable.
"If he could do it — and since I am already inside this game — then even as a mayfly, I will bite off a corner of that sky or die trying."
Lin Mu bit down hard on the tip of his tongue. The sharp pain jolted his exhausted nerves awake.
"Again."
His blood-covered hands reached out and picked up two fresh Metal Path practice Gu worms.
Another grueling deep night.
A full week had passed since the start of this closed-door session.
The air inside the chamber had grown almost solid. Only Lin Mu's faint, measured breathing moved through it.
Every last piece of cheap Metal Path material on the stone table had been consumed.
This was the final set.
In midair, two Rank 1 Metal Path Gu worms, wrapped in Red Iron Primeval Essence, had dissolved into a blazing, violently thrashing mass of golden light.
But this time, Lin Mu's Primeval Essence output had changed.
Gone was the gentle, "inclusive" approach he had used for Earth Path.
Faced with the savage, razor-sharp metal energy, his Red Iron Primeval Essence transformed into a net — immensely tough, carrying a suppressive force.
Lin Mu's eyes were cold. His ten fingers moved with rapid, precise rhythm, like a musician plucking strings.
His Primeval Essence, with a precision refined to the finest possible degree, cut and combed through the two wills — and forced them together.
"Feed the catalyst."
Without a moment's hesitation, Lin Mu scattered the final handful of Primeval Stone fragments with perfect precision into the brightest core of the light mass.
Hiss — Hummm!
The blinding light imploded with a sudden, violent inward contraction. For one instant, the entire chamber seemed drained of all color.
Then, gradually, it dimmed.
A Rank 2 basic Metal Path Gu worm — its body a deep gold, the edges of its shell sharp as a blade — settled into Lin Mu's blood-streaked palm with the quiet docility of something finally tamed.
Done.
This meant that after another enormous expenditure of Primeval Stones and a week of bloody, grinding torment, Lin Mu had finally gained a rudimentary feel for Gu refinement.
Ding.
Lin Mu didn't even glance at the practice Gu worm that had cost him so dearly. He set it aside on the table without ceremony.
He straightened slowly, not bothering to wipe the sweat from his forehead.
In those deep, dark eyes, exhaustion was gone. What remained was a cold, keen light — like the edge of a blade drawn from its sheath.
He turned.
His gaze, sharp and unwavering, fell at last upon the center of the stone table.
Two Gu worms waited there in silence, awaiting their fate.
The Vital Iron Leaf Gu. And the Rank 1 Metal Rend Gu.
"Warm-up is over."