The sharp pang in Lin Ke’s knuckle felt like an iron wedge being driven between two paving stones.
He held his left hand flat, staring at the visible sour note in his flesh. The middle finger bone of his index finger was rigid, dark, and heavy as a cast-iron bolt. The adjoining proximal knuckle was swollen, pale, and quivering under sheer clockwork tension.
Outside the heavy iron blast door, the banging was relentless.
“Lin Ke! Please!” Shen Yue’s voice was muffled through the four-inch timber core and sheet iron. “The inks are exploding on the drying racks! My hands... I can’t hold the brush!”
“Hold your position at the outer grate,” Lin Ke called back, his voice steady despite the sweat dripping from his chin. “Ten breaths. Don’t touch the locking levers.”
He couldn’t open the door yet. If he gripped the heavy iron draw-bolt with his left hand in its current state, the unequal torque would shear the proximal joint fully out of its capsule.
Material slope analysis, his mind raced.
When an engineer joins high-thickness alloy to low-thickness composite, a direct, sharp screen creates an infinite stress concentration factor. In aerospace turbine blades, you never bolt cast hardened carbon-iron directly to silver-steel. You use a functionally graded material. A nonstop compositional buffer that bridges the clockwork properties across a controlled distance.
Tianfu. Branch.
In the grey sandbox, Lin Ke analyzed the joint.
The middle finger bone had an elastic modulus near two hundred gigapascals. The untreated base finger bone was sitting at barely twelve gigapascals, filled with crumbly, hardened lime.
To bridge that terrifying canyon without a full-body merge, he needed a three-tier transitional tempering slope.
Tier One: Dense Ashen Iron Lattice at the core of the middle finger bone.
Tier Two: A micro-porous, softer iron chelate zone extending a tiny fraction of an inch into the articular joint padding of the joint head.
Tier Three: Micro-perforations through the untreated proximal bone-skin. He allowed tension-relieving elastic spreading until the full merge could be carried out.
Lin Ke cut the mental branch.
He slipped his right hand into his pocket, drew his iron metal pen. Then he pricked his thumb pad once more.
“Branch checked: main.”
Moving with cold, razor-sharp haste, Lin Ke took two fine bronze acupuncture needles from his medical kit. He dipped their tips into a dilute wash of Red ink flux and cold spring water.
Without hesitating, he drove the first needle directly into the side of the swollen knuckle, angling the tip forty-five degrees down to the bone surface of the untreated base bone.
Crunch.
A dull, nauseating ache flashed up his arm. Lin Ke didn’t blink. He gave the needle a half-twist. That created a tiny channel to vent the trapped high-pressure fluid that had built up around the stressed joint capsule.
A drop of clear, high-pressure joint fluid hissed out, followed by a dark speck of hardened grit.
He pushed in the second needle on the opposite facet of the knuckle. He formed a cross-vent.
Instantly, the choking shear tension collapsed.
The throbbing eased. The base bone settled into posture with the rigid Ashen Iron finger bone, the clockwork stress diffusing across the bone-skin channels rather than focusing on a single brittle fracture plane.
He bent his left hand.
The finger curled smoothly. The joint was stiff, but it held.
Seventy-two hours, he logged. A temporary hotfix. The entire skeleton must be committed atomically, or the next heavy load will tear the joints apart from within.
Lin Ke rose from the anvil, walked to the blast door. Then he lifted the heavy timber locking bar with both hands.
The iron door swung inward with a low, metal groan.
Shen Yue stumbled into the cellar, nearly falling to her knees on the cold flat stone slabs.
The young magic charm scribe was trembling from head to foot. Her pale, delicate face was streaked with soot and tears, her hair wild and singed at the temples.
She held both hands out in front of her, palms up, shaking wildly.
Her fingers were blistering, covered in angry red chemical burns and black scorch marks. Bits of charred yellow magic charm paper were stuck to her raw skin, sizzling faintly with leftover, volatile spiritual fire.
“Shen Yue,” Lin Ke said, his voice dropping into a calm, grounding rhythm. “Breathe. Sit on the chest.”
He guided her to a wooden storage box, grabbed a clean linen cloth. Then he soaked it in Apothecary He’s cooling spring water.
“It... It exploded,” Shen Yue sobbed, her voice hitching with terror. “I was drafting the monthly batch of Stone-Skin Ward Magic charms for the mining crews. Five sheets on the drying rack... They suddenly began to smoke. Then they all blew up together! The blast threw me across the workshop!”
Lin Ke gently pressed the cold, wet linen against her burned palms.
Shen Yue winced, biting her lip, but the icy herbal water right away drew out the stinging heat.
“Show me the paper scraps,” Lin Ke said.
Shen Yue reached into her stitched satchel with trembling, burned fingertips. Then she pulled out a handful of charred fragments.
Lin Ke took a piece of the unburned edge between his fingers.
He didn’t need a magnifying lens. He brought the paper to his nose and inhaled.
A faint, greasy, sweet scent masked the smell of red stone and soot.
Lead-grease, Lin Ke identified right away. Heavy stone oil soaked with lead oxide.
“Where did this batch of vermilion ink come from?” Lin Ke asked, his eyes darkening.
“The... The Central Supply Depot,” Shen Yue stammered, wiping a tear from her cheek. “Elder Wu told me the Grand Fortune Clan delivered twelve jars of ‘Standard Sect Red ink’ yesterday morning to fulfill their supply promise. He said it was approved by the Outer Market Checker office.”
“It’s sabotaged,” Lin Ke said flatly, tossing the paper scrap onto the workbench. “They doped the red stone mid-air with heavy-duty lead-grease.”
Shen Yue looked at him with wide, blank eyes. “Lead-grease? Why? What does that do to the ink?”
“Inherent insulating disruption,” Lin Ke explained, keeping his terms strictly grounded. “Magic charm crafting needs clean, uniform flow rate across the paper surface so your dual soul-threads can complete the circuit at the same time. When you introduce heavy lead-grease, the stone oil creates pockets of high spark pushback.”
He pointed to the charred scorch marks on the paper.
“Your soul threads didn’t align. The left thread completed the circuit while the right thread was blocked by an oil pocket. That desynchronization caused an energetic conflicting flame—a total backfire. The paper didn’t dry. It short-circuited and ignited the red stone.”
Shen Yue pulled her knees to her chest, shivering beneath her robes.
“If I can’t deliver sixty ward magic charms by the end of the week... The mining crews won’t go into the lower shafts. And the Checker office will cite me for incompetence. They’ll revoke my magic charm apprentice pay...”
She buried her face in her hands, her shoulders shaking. “Zhao Wuji is choking everything. The coal. The lime. The ink. He’s going to strangle the entire Seventh Ward, and there’s nothing we can do.”
Lin Ke stood in the center of the cellar, his dark shape cast long and dark against the fiery rock by the flickering lamp.
He looked down at his left hand. At the slate-grey index finger that had just withstood a two-pound hammer strike without a scratch.
“There’s always something we can do,” Lin Ke said, his voice quiet, steady, and razor-sharp. “Zhao Wuji controls the commercial supply chains because he thinks the sect’s official formulas are the only way to manufacture materials.”
Lin Ke walked over to the corner of the cellar. There, a massive iron collection hopper sat beneath the main chimney pipe of Crucible Four.
He reached inside the hopper and scooped up a double handful of fine, dark grey powder that felt as light as talc and clung to his fingers like dry silk.
“What’s that?” Shen Yue asked, sniffing through her tears.
“Magnetic iron dust,” Lin Ke replied, letting the powder slip through his fingers back into the bin. “The finest fine dust exhaust from our high-heat iron taps. Specks smaller than two hundred mesh, soaked with natural magnetic flow-charge.”
He looked at Shen Yue’s blistered hands, then down at the three sacks of pure Red ink flux he had purchased from the Silver Scales Pavilion.
“They took your ink,” Lin Ke said. “So we’re going to build an ink they can’t understand. An ink with a physical master interlock.”