I Was Summoned to Die, so I’m Climbing the Pantheon for Revenge!

The grinding screech of the ancient bronze doors echoed through the subterranean cavern, a sound that should have heralded a dark abyss of stone, blood, and bones. Yet, as the massive valves swung fully inward, the absolute darkness they expected did not swallow them. Instead, a blinding cascade of golden radiance poured through the threshold, forcing Shiori and everyone behind her to blink rapidly against the sudden glare.

When their vision cleared, the collective breath of the expedition caught in their throats.

"What... what kind of illusion magic is this?" Gareth 'Ironhide' growled, his heavy tower shield lowering by a fraction of an inch as his scarred face contorted in sheer disbelief.

Before them did not lie a desolate boss chamber, but a colossal, breathtaking forest stretching out beneath a vibrant blue sky. High above, a perfect, artificial sun hung suspended, bathing the lush canopy in a warm morning glow. A soft, cool breeze rippled through the sea of emerald leaves, carrying the earthy scent of pine and wild lilies. The gentle wind stirred Shiori’s long, flowing locks, unveiling the soft lavender highlights hidden underneath.

Her hair had not returned to its original, deep black. The lingering toll of using her catastrophic Ultimate Skill, Event Horizon, during their previous trials still heavily affected her mana circuits, a permanent physical reminder of the heavy price of her power.

"Everyone, do not drop your guard!" Shiori’s voice rang out, sharp and unyielding, cutting through the awe that had paralyzed the party. Her lavender-highlighted hair fluttered as she narrowed her eyes at the idyllic landscape. "A peaceful facade in a high-tier dungeon is far more dangerous than an open graveyard. This room is an spatial anomaly. If it is large enough to contain an entire ecosystem, whatever boss rules this domain is either colossal, or possesses power beyond anything we’ve simulated."

"Look at the sky," Elara whispered, her elven eyes scanning the horizon as she kept an arrow notched to her bow. "Those are real birds. Small sparrows and finches... their mana signatures are completely mundane. They aren't magical constructs."

The party began to advance, stepping off the cold dungeon stone and onto soft, dew-kissed grass. They forged a straight path through the dense, towering trees. Everything felt entirely too real. A crystal-clear stream wound its way through the undergrowth, its gentle bubbling mixing with the chattering of squirrels nesting in the high branches. Harmless forest animals—deer, rabbits, and small badgers—wandered lazily through the bushes, completely unbothered by the arrival of heavily armored invaders.

"If any beast approaches you, do not hesitate. Avoid them if possible, but eliminate them if they cross our perimeter," Shiori commanded in a low hiss, her hand firmly gripping the hilt of her broadsword. "In an active boss zone, there is no such thing as an innocent creature."

"Hey... look at that one," Shota murmured, pausing as his eyes caught a sleek, silver-furred wildcat perched on a mossy boulder.

The wildcat sat perfectly still, its amber eyes locked onto Shota with an eerie, unblinking intensity. Shota, who possessed a deep, hidden fondness for felines in his original world, felt a momentary twinge of hesitation. He wanted to believe it was just a harmless animal, a part of the beautiful nature around them. He needed to act like a hardened, summoned Hero, but his heart wavered.

Suddenly, the wildcat’s muscles tensed. With a feral, guttural screech that defied its small size, the beast launched itself off the boulder, its claws extended directly toward Shota’s throat.

Thwack!

A gale-force gust of wind ripped past Shota’s ear as Elara’s arrow pierced the wildcat mid-air with flawless, lethal precision. The beast was violently pinned to the dirt, coughing up crimson blood before going completely still.

Shota shook slightly, his breath hitching as he stared at the dead animal. The bleeding was real. The meat was real.

"Shota-kun! Focus!" Shiori snapped, her sharp gaze locking onto him. "That was a direct predatory strike. There are no illusions here. Every single creature in this room is bound to the will of the floor boss. Move!"

"Right... sorry," Shota muttered, pulling his dual daggers and stepping back into formation. Internally, his mind raced. If that cat wasn't a magical illusion... what is this place? Is the dungeon replicating a true piece of Earth, or did it swallow a forest from this world whole?

They continued to press forward into the dense woods, the eerie juxtaposition of natural beauty and lethal tension gnawing at their nerves. But as they ventured deeper, the atmosphere began to subtly shift. The warmth of the morning sun seemed to lose its heat. The air grew progressively heavier, turning thick and suffocating, tasting of static electricity and damp earth. The cheerful chattering of the squirrels died out. The birds stopped singing. The only sound remaining was the heavy, synchronized thud of their own armored boots.

And then, it started.

Plink.

A single, crystalline note cut through the suffocating dampness of the silent forest.

Shiori froze instantly, her hand snapping up to signal a halt. Her knuckles turned white against the grip of her sword.

Plink. Plink. Plink.

It wasn't a random, structural echo. It was music. Slow, heavy, metronomic triplets began to drift through the towering trees, echoing down from the canopy. The melody was devastatingly cold, dripping with an ancient, unbearable sorrow that seemed to seep into the very marrow of their bones, wrapping around their hearts like icy vines.

"Is that... a piano?" Shota whispered, his voice trembling as he looked around frantically. "Deep inside a high-tier dungeon boss room? That’s impossible... pianos don't exist in Frontierra!"

"Stay sharp, don't let the rhythm dictate your breathing!" Shiori commanded in a low hiss, cold beads of sweat forming along her forehead. "This is likely a high-tier mental interference spell disguised as sound. Mages, cast your anti-cognition barriers!"

The native adventurers quickly began to chant defensive incantations, but Boran, the greedy-eyed human Mage, stopped mid-sentence, his jaw dropping. "H-Hero Shiori... there is no mana in the air. My detection runes aren't reacting. There is no spell casting happening!"

Shiori’s breath hitched. Boran was right. The ambient mana was completely stagnant. This wasn't a magical curse or an automated trap. It was pure, unadulterated talent. Someone—or something—was sitting in the absolute heart of this monster-infested hell, playing a grand instrument with flawless, terrifying precision.

And Shiori knew exactly what the song was. It was a tune burned into the cultural consciousness of Earth.

Beethoven’s Moonlight Sonata. Adagio sostenuto.

The tragic, sweeping tune felt like a localized funeral march, explicitly written for the specific party that had just walked into its domain. The native Frontierra adventurers were completely bewildered; they had never heard such a complex, mathematically perfect yet emotionally devastating instrument. They didn't even have a word for a piano. To them, it sounded like a haunting, multi-layered harp played by a god of death.

Suddenly, the simulation above them shattered. The golden sunlight vanished in a flash as the sky turned into a churning sea of dark, bruising clouds. The false sun was blotted out, plunging the grand forest into a deep, twilight gloom. The animals completely vanished, leaving the woods entirely barren.

The first movement faded into an absolute, ringing silence. The quiet was deafening, dominating the massive room as the party stood frozen, completely paralyzed by anticipation.

Then, the second movement—the Allegretto—began to play.

The music shifted, becoming lighter, almost playful, yet inherently deeply unsettling in its context. The notes seemed to spread from everywhere and nowhere at once, bouncing off the trees, rising from the grass, and descending from the dark clouds.

"Check for toxins! Check for hypnotic frequencies!" Shiori ordered, her eyes darting across her status screen.

Yua checked her holy diagnostic magic, her hands glowing with a soft white light. "Nothing, Shiori-san! No poison, no sleep status, no hexes. It’s... it’s literally just music!"

Why? Shiori thought, her mind racing as she analyzed the empty forest around them. What is the purpose of playing this specific masterpiece here? Is the boss a summoned Hero from Earth who went rogue? Or is the dungeon using the stolen memories of past heroes to mock us?

Before she could find an answer, the Allegretto came to a sudden, abrupt halt.

Once again, an absolute, terrifying quiet dominated the entire spatial chamber. The silence lasted for only three heartbeats.

Then, the final movement erupted. Presto agitato.

The piano didn't just play; it exploded into a frantic, tempestuous storm of rapid, pounding notes. The music was a violent assault of relentless arpeggios and crashing chords, unleashing a wave of raw, unchecked fury.

Instantly, the lack of magic didn't matter. The psychological weight of the masterpiece, amplified by the sheer, suffocating pressure of the dungeon's true hidden aura, struck the party like a physical blow.

"Ah... AHHG!" Shota suddenly gasped, dropping his daggers as his knees buckled. He slammed into the dirt, clutching his head frantically as his eyes widened in sheer panic.

It wasn't a magical curse; it was a psychological trigger. The frantic, aggressive tempo of the Presto agitato induced an immediate, overwhelming wave of paranoia and suspense. Every single member of the party felt their heart rates skyrocket into dangerous territory, their pulses hammering like war drums against their ribs.

"Get up! Stand up!" Gareth roared, but even the massive Vanguard was struggling. He sank down onto one knee, using his massive tower shield as a crutch as the invisible, psychological gravity of the song crushed him. The air felt ten times heavier, the weight of his own armor suddenly feeling like an anchor dragging him into hell.

All around them, elite adventurers and summoned heroes alike were kneeling in the dirt, clutching their temples, some screaming in sheer, unadulterated despair as the tragic, frantic notes tore through their minds, exposing their deepest fears and insecurities.

Only Shiori remained fully standing, though her legs trembled violently under the crushing weight of the atmosphere. Her lavender-highlighted hair whipped around her face as she forced her eyes open, staring through the dim, dark forest toward the source of the music.

The Presto agitato continued to roar through the trees, a relentless storm of keys, welcoming them to the true nightmare of Floor 50.

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