​The journey north across the frozen expanse took two full days.

​As they drew closer to the cavern’s mouth, the forest’s atmosphere shifted drastically. A heavy silence descended—not a peaceful silence, but one that pressed against the eardrums. There was no fluttering of bird wings, no chirping of crickets. Even the wind seemed reluctant to blow among the stiff, frozen trees. Dry branches rubbed against each other overhead, creating a sound—creak... scratch...—that felt like hoarse whispers coming from every direction. In the midst of this eerie stillness, the roar of tank engines and the growl of transport vehicles were the only anchors connecting them to the outside world.

​Inside the command vehicle, Rianor Sudrath sat with his back straight. The blue light from his crystal tablet reflected off his glasses. On the screen, the map of Project Legion was displayed—lines and coordinate points he had already memorized. However, thanks to the data from the Mana Core, new dashed lines now dissected the dark levels deep underground. It was an estimate, a path leading into the unknown.

​Beside him, Arvid kept flipping through his worn notes. His slightly trembling fingers traced line after line of ancient script. He muttered something—perhaps a mantra or just the pronunciation of a dead language—then scritch, he crossed out a line and wrote a new note on the yellowed margins of the paper.

​In the front seat, Riven sat with his arms crossed. His eyes stared straight at the snow ahead, his jaw tightening with an expression that was hard to read. Rianor knew that look. Riven was always the quietest man before the storm broke. It wasn’t because he was afraid, but because he was gathering fragments of memory.

​"Do you... still remember the way in?" Rianor asked, breaking the cabin’s silence.

​Riven didn’t turn immediately. He took a short breath through his nose. "I remember." A brief pause. "I also remember who never made it out."

​The convoy continued to crawl forward. The forest grew denser; giant trees with interlocking branches blocked the sky, making the remaining sunlight a mere pale twilight. The air began to feel different.

​Some soldiers in the rear vehicles began to show signs of restlessness. Their fingers tapped against their rifle barrels in a quick rhythm. Their eyes darted wildly, scanning every shadow among the trees. They didn’t know what waited ahead, but their primal instincts were already screaming warnings.

​In the lead scout vehicle, Khulafa sat with his back against the metal wall. His eyes were half-closed, but all his senses were sharpened. He didn’t listen with his ears, but with the predator’s instinct honed over years of survival.

​Suddenly, his back stiffened.

​"Halt."

​Khulafa’s voice crackled over the radio. Calm, almost a whisper, yet Rianor knew that tone meant death was close.

​The convoy came to a sudden stop. One by one, the engines were shut down until silence reigned once more—this time, it was even thicker. Even the sound of branches rubbing together vanished, as if nature itself was holding its breath.

​"Movement," Khulafa whispered through the Vibro-Comm. "Non-human. Two o’clock. Three points."

​Rianor narrowed his eyes in the direction indicated. Behind the thicket, in the deep shadows, something moved stiffly. Creak... creak... The sound of metal legs piercing the ground was faint. It wasn’t the movement of a breathing creature; it was a mechanical, precise motion.

​"Stray Crawlers," Riven growled. He was already on his feet, his hand reaching for the handle of the mechanical axe on his back. "Hmph, they’ve gotten bold enough to come out."

​Rianor immediately grabbed the radio, his voice measured and cold. "All units, battle stations. Thorne, form a barricade around the vehicles. Dom, Ghost Squad to the roof. Do not fire until my command."

​"Understood."

​From the darkness of the forest, three figures crawled out. Stray Crawlers—a more compact version of the Obsidian Crawlers that had nearly claimed Riven’s life. They were about three meters long, their bodies encased in black metal plates speckled with rust at the joints. Six legs on each side dug into the ground, creating small holes with every step. At the head, grinding mandibles spun slowly—whirrr... whirrr...—emitting a piercing, high-pitched hum. Their red eyes glowed dimly, scanning the convoy like predators finding prey.

​The monster in the middle, slightly larger than the others, emitted a high-pitched screech. Echolocation. The sound waves bounced off the trees, telling them the exact position of every human there.

​"Riven," Rianor called out shortly.

​"Yeah."

​"Destroy them."

​Riven leaped from the vehicle even before Rianor finished his sentence. His mechanical axe roared to life—vroom!—its serrated blades spinning madly at 3,000 RPM, ready to pulverize anything in its path.

​He landed with a heavy thud right in front of the first Crawler. The metal creature raised its sharp front leg, preparing to spear him. But Riven was faster. His axe swung horizontally, striking the monster’s head right between its red sensor eyes. Crack! Sparks flew violently, followed by a spray of thick black fluid—oil mixed with synthetic blood that smelled rancid. The Crawler’s head split open, and its massive body collapsed onto the ground with the sound of metal clashing against stone.

​The second Crawler lunged from the side at high speed. Riven didn’t dodge. Instead, he delivered a powerful kick to the opponent’s rusted front leg until it snapped like a dry twig. With a spin of his body, he slammed his axe down. Once, twice—on the third strike, the engine inside the Crawler’s body suffered a small explosion and it ceased to move forever.

​The third Crawler, the largest of the three, tried to break through toward the command vehicle, targeting Rianor. However, before it could leap, three cracks of Gauss Rifles barked from atop the vehicle. Thung! Thung! Thung! Dom, Ruslan, and Naya fired with high precision. The magnetic slugs pierced the Crawler’s armor like a hot knife through butter, shattering the core circuits within. The creature slumped, its legs twitching wildly for a few seconds before dying completely.

​Silence fell once more.

​The roar of Riven’s axe faded into a soft hum. He wiped the remnants of black fluid from his blade with his sleeve, his eyes still wary. "Tsk, is that it?"

​"For now, perhaps." Rianor climbed down from the vehicle, approaching the monster’s wreckage. He flipped a piece of metal that was still hot with the tip of his boot. "They’re appearing on the surface more frequently. Before, they never dared to come out this far."

​"They’re evolving," Arvid said, standing beside Rianor, his face pale. "Or perhaps... the population inside is so overcrowded that they’re starting to spill out."

​Thorne approached with quick steps. "One soldier injured, My Lord. Hit by hot metal shrapnel when the second Crawler exploded."

​"Is it severe?"

​"Minor. Only the left arm. The medical team is handling it."

​Rianor nodded. He walked toward the medical vehicle, checking his own equipment. Tubes of healing potions were neatly arranged, enough for twenty people. Antiseptic bandages and sterile emergency surgical tools were also prepared. These three days of preparation could not be flawed by a single oversight.

​The injured soldier—a youth named Kell who hadn’t even reached nineteen—sat on the edge of the vehicle while his wound was bandaged. His face was pale, but his hands still gripped his rifle tightly.

​"Can you still go on, Kell?" Rianor asked, soft but firm.

​Kell looked up, trying to straighten his back. "I can, My Lord. I can still shoot."

​Rianor stared into the boy’s eyes for a moment, then patted his shoulder. "Good. Keep your focus."

​The cave entrance hadn’t changed much.

​Hidden behind dry brush that now grew taller, the giant stone door still stood firm, supported by ancient pillars whose surfaces were cracked by time. Dry moss covered the walls, and tree roots began to crawl into the gaps in the stone. Yet, its essence remained the same: chilling.

​On the plateau, the remains of the first expedition camp were still scattered. Tents torn by the wind, the fabric rotted and faded. Rusted equipment—pickaxes, old lanterns, tin plates—lay haphazardly. And among the debris...

​Corpses.

​The skeletons remained in their original positions. Some still wore the remnants of Iron Mercs uniforms that had disintegrated, yet the crossed-swords-on-a-shield emblem was still recognizable. Their poses were strange. They didn’t die in fighting positions or while fleeing. Some sat leaning casually against rocks; others lay beside their work tools. It was as if their lives had been snatched away while they were in the middle of a beautiful dream.

​Riven stopped in front of one skeleton. There was a rough patch on the left shoulder of that uniform—something he remembered the owner had sewn himself.

​"Marbas..." Riven murmured softly. His voice sounded heavy.

​Rianor stood beside him in silence. He knew the story. Marbas was the first victim of the Mind Flayer’s cruelty here. The creature had harvested his fears, twisting his memories of his deceased wife and child until he died in a happy illusion. Now, the illusion was gone, leaving only nameless bones.

​Arvid approached the cave wall, observing the symbols carved deep into the stone. "Hmm, this is an authentic warning. ’Do not enter without authorization. High-level biological hazard. Level 5 personnel only.’ The dialect is exactly the same as what we found in the Silent City."

​"Can you translate the rest?"

​"Most of it, yes. The rest..." Arvid stared into the dark corridor within. "I might need more light inside."

​Rianor walked toward the legendary Adamantite Gate. Its surface was pitch black, cold, and entirely untouched by rust despite thousands of years of exposure. He reached into his bag, taking out The Sentinel’s Mana Core. The blue core throbbed softly—thump... thump...—like the heartbeat of a patient machine.

​As soon as he pressed the core to the panel beside the gate, a miracle happened.

​There was no sound of a crash. No violent vibration. Only a flow of blue light that quickly traveled along the carved patterns on the gate, like electricity flowing through an ancient circuit. Symbols that were once dead now glowed brightly, illuminating the surrounding area. With a soft hiss, the giant gate slid slowly, opening inward.

​Sshhh...

​A blast of cold air rushed out from within, carrying the scent of metal, ozone, and the musty smell of flesh that had rotted thousands of years ago. It was the smell of death, perfectly preserved.

​Thorne immediately gave the command. One by one, the lights on the soldiers’ helmets flickered on, piercing the darkness ahead. However, the light seemed to be sucked in; the darkness in here felt far denser than the night outside.

​Rianor turned toward his team, his face grimly serious. "Activate the White Noise in your helmets. Do not turn it off—not even for a second. You all know what happened to those who heard the ’whispers.’"

​Some soldiers swallowed hard. Gulp. They all knew the stories of comrades attacking comrades because of illusions. Of voices calling from the darkness. Those stories were no longer fairy tales, but a reality standing before their eyes.

​Riven stepped forward first without a moment’s hesitation. He leaned his mechanical axe against his back again, his hand ready to draw it in a split second. Dom and the Ghost Squad followed behind with Gauss rifles raised. Thorne signaled the infantry to close ranks in battle formation.

​Arvid snapped his book shut. His face was deathly pale, but he didn’t back down. He glanced at Rianor for a moment.

​"Are you ready, Professor?" Rianor asked softly.

​Arvid took a long breath, trying to calm his racing heart. "No. But well, here I am."

​Rianor almost smiled. Almost.

​He was the last person to cross the threshold. Stopping for a moment, he stared into the black hole ready to swallow them all. The cold wind hit his face again, carrying unfinished whispers from the past. Before him, the greatest mystery of this civilization awaited.

​The light on his helmet shone bright, and the darkness swallowed him.