The Steel Undead of the Mechanical City Ruins and the Battle for the Core

[System notification: Main quest "Explore the Mechanical City ruins" activated. Objective: venture deep into the heart of the ruins, reclaim the Source Energy Core occupied by the Steel Undead, and restore Mechanical City's energy system. Time limit: 48 hours. Reward: unlock the Mechanical Affinity talent, increasing the team's efficiency at operating mechanical devices by 50%. Failure penalty: the ruins' automatic defense system will classify you as intruders and permanently seal the plane passage.]

Chapter 1: Iron Filing Storm at the Rusted Entrance

The entrance to the Mechanical City ruins looked like a metal wound that had been gnawed open. Broken pipes periodically spat steam laced with sparks, and a rust-covered alloy door hung crookedly from its hinges. Of the three large titanium-gold characters spelling "Mechanical City" above the door, only "machine" remained legible. The pungent stench of machine oil, rust, and ozone filled the air. Steel plates creaked underfoot, and loose bolts occasionally fell from the steel framework overhead.

"Watch your step." Lu Mu crouched and used a multitool to pry up a warped steel plate, exposing a dense tangle of wires beneath it. Blue sparks darted between the copper strands. "The wiring here is a complete mess. One wrong step could trigger a short circuit." He pulled out a palm-sized "circuit detector," and red danger zones and green safe paths immediately appeared on its screen. "Follow the green lines. The detector has a range of fifty meters. Call me if you go beyond it."

Xiao Yan held the Core of Elements he had just brought out of the Elemental Prison. The five-colored light on its surface rippled when it came into contact with Mechanical City's metal. "This core can absorb energy from its surroundings, including the electricity leaking from these wires." He held the core close to a sparking cable. The sparks were instantly sucked into it, and the exposed copper wire slowly cooled. "Perhaps we can use it to temporarily disable some low-level defenses."

Suddenly, mechanical clacking came from the tall, rusted walls on both sides of the entrance. Hundreds of rusty metal nozzles sprang out of the walls and aimed at the center of the entrance. What they sprayed was not flame or bullets, but a sky-filling cloud of iron filings. Accelerated by high-pressure air, the filings sliced through the air like sharp blades and struck the steel plates with crisp, crackling snaps.

[System notification: Iron Filing Storm trap encountered. Duration: 10 minutes. Recommendation: use metal defenses to block it, or find a blind spot in the rusted structure.]

"Use the Elemental Core!" Xiao Yan raised the core above his head. Its five-colored light formed a hemispherical barrier, and the iron filings that struck it fell to the ground, piling up in a thin layer of metal powder. Wu Hao hefted a giant alloy shield he had picked up beside the entrance-it looked like the hatch of an old-fashioned defense tower-and said in a muffled voice, "This shield's thick enough. I'll cover the rear!" He held it at an angle, and the filings bounced off its surface, gouging countless little pits into the steel plates behind him.

Lin Xiuya's sword spun in his hand, leaving a ring of afterimages. His sword Qi split the stray iron filings that slipped past the barrier into even finer powder. "There's a ventilation duct in the left wall! It's big enough for one person to crawl through, and it'll get us out of the storm!" He pointed to a square duct opening three meters up the left wall. Its grate had rusted and broken. "I'll scout ahead. Cover me with the core!"

His sword flashed, and Lin Xiuya darted to the duct opening. He flicked the grate away with his longsword, then vaulted inside. His muffled voice came from within. "No traps in here, but it's a little narrow. We'll have to crawl!"

Xiao Yan called to the others, "Lu Mu, bring up the rear and use the detector to find a route. Wu Hao, cover us with the shield. Zi Yan, stay in the middle with me and use the Dragon Phoenix Flame to melt any rusted-shut parts that might block us!"

The Elemental Core's barrier moved slowly, sheltering the group within it. Zi Yan spat out Dragon Phoenix Flame from time to time, melting the rust around the edge of the duct opening. "These iron filings are really tough. The flame won't melt them unless it's hot enough!" She flicked her tail, which had been struck by the filings. A few stubborn specks clung to her scales. "If only I had a hotter flame."

"Try the Elemental Core's fire attribute!" Xiao Yan turned the core toward Zi Yan. The red light on its surface suddenly brightened, and a stream of scorching energy flowed from the core to her. Her Dragon Phoenix Flame instantly turned a blinding white. "Wow! That's hot!" She spat a small cluster of white flames at the duct opening, and the rust around its edge instantly melted into molten iron. "It's clear!"

Ten minutes later, the Iron Filing Storm gradually subsided, and the group crawled into the ventilation duct one after another. It was pitch-black inside. All they could hear was one another's breathing and the rustle of friction against the steel plates. Lu Mu's detector screen suddenly lit up red. "Signs of mechanical activity fifty meters ahead. There are... at least twenty!"

[System notification: Tier One Steel Undead · Rusted Infantry encounter imminent. Level: Dou Wang. Traits: bodies composed of rusted metal; attacks carry "tetanus" toxin. Weakness: exposed gears at joint connections.]

Chapter 2: The Rusted Infantry Swarm in the Gear Corridor

The group crawled out of the ventilation duct and dropped into a corridor about ten meters wide. Countless sets of gears were embedded in the walls on either side. The largest were nearly three meters across, while the smallest were no bigger than a fingernail. All of them turned slowly in the same direction, shedding rust from between their teeth as they rotated. It piled up on the floor like a layer of "rust sand." The gate at the end of the corridor was shut tight, its surface engraved with intricate gear patterns. Clearly, it needed specific gear keys to open.

"Looks like we have to find matching gears to open the gate." Lu Mu ran his hand over the patterns. "These are Three-Stage Linkage Patterns. Three gears of different sizes have to be fitted into the upper, middle, and lower slots, and their teeth have to match the patterns exactly. Even one tooth off won't do."

No sooner had he finished speaking than the gear sets on both sides of the corridor began turning faster. With a series of clacks, twenty Rusted Infantry squeezed out of the gaps between them. Their bodies were cobbled together from all sorts of discarded parts. Some wore battered welding masks as helmets, their arms made from rusty hydraulic steel pipes and their hands clutching broken chainsaws. Others had mismatched tracks for legs and limped as they moved, swinging rusty wrenches. Most conspicuous of all was a big fellow with a crane boom on its head. A giant electromagnet hung from the end, sizzling as it pulled iron filings off the floor.

[System notification: Rusted Infantry swarm attack mode activated. Beware the electromagnet model's Magnetic Attraction skill.]

"Split into two groups!" Xiao Yan made an immediate decision. "Wu Hao, Hu Gan, hold off the big one with the electromagnet. Use the Elemental Core's earth attribute to suppress it-earth can block magnetic force! Lin Xiuya, Zi Yan, help me clear out the smaller ones and find the gear keys! Lu Mu, use the detector to locate the gears!"

Wu Hao hefted the alloy shield, and Hu Gan gripped the Black Tortoise Shield. The two charged the electromagnet infantryman from opposite sides. Its boom slammed into the floor, and the electromagnet activated at once. Iron filings and bolts flew from the ground to its body, forming an "iron shell" over its surface. "Bring it on!" Wu Hao channeled the Elemental Core's earth-attribute energy into his shield, and an earthy yellow glow appeared on its face. "Watch me break your magnetism!" He smashed the shield into the electromagnet. Earth-attribute energy collided with magnetic force with a low hum, and the iron shell fell away from the electromagnet, exposing the bare coils inside.

"Now!" Hu Gan punched the coils, unleashing the power of the Black Tortoise. The coils buckled instantly, the electromagnet failed completely, and the boom dropped with a clang.

On the other side, Xiao Yan's Heavenly Flames, wrapped around the Elemental Core's fire attribute, became a fire dragon that charged into the swarm. The Rusted Infantry's metal bodies caught fire on contact, but instead of turning to ash, they melted and warped in the heat, sticking together. "Zi Yan, burn their joints!" Xiao Yan shouted. Zi Yan aimed her Dragon Phoenix Flame precisely at the gears in the infantrymen's knees. The gears expanded in the heat, jamming their tracks and steel-pipe legs. Many infantrymen collapsed on the spot, able only to wave their arms without moving an inch.

Lin Xiuya aimed his sword exclusively at the gaps between gears. Whenever its light flashed, it sent several crucial gears flying, making an infantryman instantly fall apart. "Found one!" He pried a palm-sized gear from an infantryman's chest. It was marked "17 teeth." "Lu Mu, see if this is one of them!"

Lu Mu scanned the gear with his detector. The screen immediately displayed: "Matches the lower slot in the gate. Tooth count correct! Upper slot (23 teeth) and middle slot (31 teeth) still needed!"

The battle lasted nearly half an hour, leaving the corridor piled with the Rusted Infantry's "corpses"-really just heaps of scattered parts. The group searched through them for gears. Zi Yan used her dragon claws to pull apart the remains of an infantryman with a gearbox on its head and dug out a fist-sized gear. "This one! Twenty-three teeth!" Wu Hao, meanwhile, removed a larger gear from the electromagnet infantryman's head. Its teeth were clearly marked "31." "The middle one's here!"

They fitted the three gears into the gate's slots. The teeth meshed perfectly with the patterns, and the gate slowly rose, revealing deeper darkness beyond. From within came the sound of a giant gear turning, louder than any in the corridor.

[System notification: Rusted Infantry swarm cleared. Obtained: Rusted Gear ×37 (can be used to repair simple machinery). Gate opened. Entering the Drive Shaft Passage.]

Chapter 3: The Hydraulic Crushing Array in the Drive Shaft Passage

Beyond the gate lay a narrow passage suspended high in the air. It was supported by dozens of drive shafts, each nearly a meter in diameter. Spiral blades covered the shafts, spinning at tremendous speed. The gaps between the blades, only wide enough for one person, formed the "path." Rusty steel plates connected the shafts, and through holes in the plates they could see the unfathomable darkness below. Broken cables occasionally drifted through the darkness like giant centipedes.

"This passage is about a hundred meters long, and every drive shaft turns at a different speed." Lu Mu lay at the edge of a steel plate, watching red lights occasionally flash in the darkness below. "That's the scrap metal processing pit down there. Fall in, and the automatic crushing system will grind you into iron filings. And look: the edges of the drive shaft blades are sharp alloy. Touch one and you'll lose a chunk of flesh."

[System notification: Passage has triggered the Hydraulic Crushing Array mechanism. Every 30 seconds, one randomly selected drive shaft accelerates, narrowing the gaps between its blades to half a meter. Every 1 minute, all drive shafts vibrate in unison, causing cracks to appear at the steel plate connections.]

"I'll scout ahead!" Lin Xiuya shot forward like an arrow, stepping through the gaps between the blades. His sword whirled in a circle, deflecting several blades that nearly swept into him as they accelerated. "They're not that fast, but the gaps are too narrow. You have to place your feet precisely!" He reached the middle of the passage and suddenly shouted, "Careful! The third shaft on the left is speeding up!"

Sure enough, the blades on the third drive shaft to the left abruptly accelerated. The gap that had been wide enough for one person instantly narrowed, and the steel plates shook violently from the vibrations. A plate beneath Wu Hao's feet suddenly cracked, leaving half his foot hanging in midair. "Damn it!" He grabbed the drive shaft beside him, sparks flying as his alloy glove scraped against the rotating shaft. "Lu Mu, can you slow it down?"

Lu Mu pulled out a miniature "electromagnetic jammer," aimed it at the drive shaft, and pressed the switch. "Try this! It'll interfere with its hydraulic system!" The jammer crackled with electric current, and the shaft did indeed slow down, widening the gaps between the blades again. "But it only works for ten seconds! Hurry across!"

Xiao Yan hoisted the Elemental Core, and its light enveloped the group. "Follow me. Use the core's energy to cushion the vibrations!" He stepped onto the steel plate that was shaking most violently. The core's five-colored light formed a stabilizing field, and the plate's vibrations immediately weakened by more than half. "Zi Yan, wrap your dragon tail around my waist to keep your balance! Wu Hao, Hu Gan, cover the rear and watch out for cracks underfoot!"

Zi Yan did as told, wrapping her dragon tail around Xiao Yan and spreading her wings for balance. "The fifth shaft on the left looks like it's about to start shaking!" No sooner had she spoken than the shaft gave a tremendous clang. Its blades began swinging erratically, as if they were about to break.

"Jump across!" Xiao Yan made an immediate decision and leaped with the Elemental Core in his arms. Zi Yan's dragon tail snapped with force, flinging them both toward the drive shaft opposite. Lin Xiuya met them ahead, bracing with his scabbard to catch Xiao Yan securely. Wu Hao and Hu Gan followed close behind. Hu Gan slammed the Black Tortoise Shield against a shaking steel plate and used the recoil to leap toward the safe area.

Just as the last person left the passage, a tremendous rumble came from behind them. The entire Drive Shaft Passage began to collapse. Blades and steel plates tumbled into the scrap metal processing pit below, and a teeth-grating crunch came from the darkness.

At the end of the passage stood a circular alloy door with a palm-sized recess. Engraved inside it were the words "Source Energy Core compatible."

[System notification: Drive Shaft Passage cleared. Obtained: Hydraulic Oil ×5 (can lubricate mechanical joints). The Core Control Room lies ahead. High-tier Steel Undead expected.]

Chapter 4: Iron King · Zero in the Core Control Room

The alloy door slowly opened at the Elemental Core's touch, revealing a shocking sight. Countless glowing energy tubes hung from the ceiling, connected to a cylindrical device about ten meters tall in the center. Its surface was covered in a layer of flowing blue liquid. It was the Source Energy Core. But standing around the core was a Steel Undead far larger than the Rusted Infantry. Nearly five meters tall, its body was made of silvery-white alloy with almost no rust. Its head was a diamond-shaped blue display screen, complex code flickering across it. It held a transformable electromagnetic blade in each hand, and six extendable mechanical arms rose from its back, each tipped with a different weapon: laser guns, grenade launchers, arc whips...

[System notification: Steel Undead leader · Iron King · Zero encountered. Level: Peak Dou Emperor. Traits: can control multiple weapons simultaneously; body covered by an "energy shield" (immune to attacks below Dou Wang level). Weakness: "logic chip" behind the head display.]

"Looks like this is the final guardian." Xiao Yan handed the Elemental Core to Lu Mu. "Lu Mu, use the core to recharge everyone and strengthen their weapons. Wu Hao, Hu Gan, keep it occupied from the front. Watch out for its arc whip; that thing conducts electricity. Lin Xiuya, circle behind it and attack its mechanical arm joints. Zi Yan, use high-temperature flames to burn its energy tubes and force it to expose the chip. I'll lead the attack on the display!"

"Got it!" The group quickly moved into position. Wu Hao and Hu Gan raised their shields and charged Iron King · Zero. The Iron King's electromagnetic blades transformed instantly, blue arcs of electricity winding around their edges as they slashed at the two men. The moment shield met blade, electricity spread along the shield, and Wu Hao's arm went numb. "Damn, that packs a punch!"

Hu Gan blocked the other electromagnetic blade with the Black Tortoise Shield. Runes lit up on its surface, barely counteracting the electric arcs. "Xiao Yan, hurry! Its mechanical arms are about to move!" Sure enough, four of the arms on the Iron King's back rose at once. Two fired grenades, and two sprayed high-temperature flames.

"Leave it to me!" Zi Yan's Dragon Phoenix Flame mixed with the Elemental Core's fire attribute and became a fire dragon that crashed into the flame nozzles. The two sources of intense heat collided, causing a violent explosion that instantly wrecked the flame-throwing arms. Lin Xiuya seized the chance to circle behind the Iron King. His sword flashed like lightning, piercing the mechanical arms' hydraulic tubes. Green hydraulic oil sprayed across the floor, and the remaining arms immediately drooped.

"Now!" Xiao Yan gathered his Heavenly Flames and the Elemental Core's five-attribute energy into a multicolored longsword. He leaped and thrust straight at the Iron King's head display. A red warning box suddenly popped up on the screen, and an energy shield instantly covered its entire body. The longsword struck the shield and bounced back.

"Its shield is too strong!" Xiao Yan used the force to retreat. "Lu Mu, interfere with its logic chip! Use the electromagnetic jammer!" Lu Mu had already set the jammer to maximum power. He aimed it at the Iron King's head and pressed the switch. The display suddenly began to flicker, its code fell into chaos, and the energy shield's light alternately brightened and dimmed.

"Found it!" Lin Xiuya pointed his sword at a gap behind the display. "The chip's right there!" Xiao Yan seized the opportunity and leaped again, gathering all the Dou Qi in his body into the longsword. "Heavenly Flames · Elemental Slash!" The multicolored sword cleaved through the unstable shield and stabbed precisely into the gap behind the display. The Iron King's screen went black at once, all its mechanical arms fell to the floor with a clang, and its electromagnetic blades returned to their original forms.

[System notification: Iron King · Zero defeated. Obtained control authorization for the Source Energy Core.]

Xiao Yan walked up to the Source Energy Core and pressed the Elemental Core against its surface. The two kinds of energy began to merge. The blue liquid on the core's surface gradually turned clear, the control room's lights came on one by one, and the abandoned screens once again displayed Mechanical City's energy distribution map.

[System notification: Source Energy Core successfully restarted. Mechanical City ruins' energy system restored to 30%. Main quest complete! Team has unlocked the Mechanical Affinity talent and obtained Iron King · Zero's Logic Chip (can be used to create high-tier mechanical devices).]

Lu Mu ran his hand over the functioning console and smiled. "Looks like it won't be long before this place is back to normal. What will the next plane be?"

Xiao Yan looked out the control room window. In the ruins that had once been pitch-black, streetlights came back on one by one, like stars fallen upon a land of steel. "Whatever it is, we can handle it."

[System notification: Team status fully restored. Mechanical Affinity talent activated. Lower Plane coordinates: Spirit Plant Realm. Countdown to teleportation: 10 minutes.]