The mundane, low-magic cavern melted away, replaced by an environment that immediately felt dangerous and suffocating.
They stood in a massive, ancient fortress carved from obsidian rock. The air was thick and cold, saturated with a palpable aura of death and high-grade magical energy. The floor was rough-hewn stone, littered with the faint residue of combat.
"The air… it's heavy," Tanjiro observed, gripping his blade. "The scent of blood and power is everywhere. It's terrifying."
"Perfect," Jin-Woo said, his voice a low, satisfied rumble. His blue eyes, which had dimmed in the low-magic swamp, now glowed with intense, electric energy. "This is a high-level magic dungeon. My world."
Gojo's eyes, visible above his blindfold, narrowed. "Not perfect. My Cursed Energy feels… restricted. Like trying to pull taffy in a bucket of cement. The air is actively draining my reserves just to exist here."
"I feel it too," Jin-Woo confirmed. "This environment is designed to suppress high-level spellcasting. We must ration our Mana and Cursed Energy. Any major release will be debilitating."
The Arbiter's voice, now echoing with the solemnity of a raid master, established the rules.
"Welcome to Trial 3: The Annihilation Raid. You must clear three floors of this Dungeon and defeat the Sentinel Boss guarding the final exit. The time limit is two hours. Failure to clear the floors results in a critical penalty."
"Kazuma-san, Okarun-san, listen closely," Jin-Woo commanded, not asking, but stating. "Your job is to identify traps and distractions. Your limited power means you won't trigger the system's suppression. Tanjiro will act as mobile defense. Gojo and I will handle the high-threat magical enemies. Saitama…"
Jin-Woo paused, looking at the hero who was already bored. "Saitama, you are our contingency. Use only minimum force, enough to disable, not destroy. We need efficiency, not spectacle."
"Fine, fine. Don't blow up the furniture. Got it," Saitama replied, adjusting his slightly singed collar.
They entered the first corridor, and the Dungeon immediately responded. Two colossal Stone Golems materialized, their bodies comprised of granite and infused with powerful magical runes that made them immune to casual physical damage.
Jin-Woo stepped forward. "I will focus fire on the runes. Gojo, draw the target's aggression."
"Aggression? You wound me, Shadow Monarch-kun. I'll make it fall in love with me!"
Gojo raised his hand, not using a Cursed Technique, but using his innate understanding of spatial forces. He flicked a pebble and guided it using minimal Cursed Energy. The pebble traveled at bullet speed, hitting one Golem's eye with a soft, thwack.
The Golem roared in offense and immediately lumbered toward Gojo. The other Golem followed.
"See? Simple provocation!" Gojo boasted, effortlessly dodging the crushing fists of the Golems.
Meanwhile, Jin-Woo, moving with blinding speed, materialized Kamish's Wrath daggers, now glowing faintly blue, and systematically carved specific runes on the Golems' backs. He was not trying to damage them, only to disrupt the magical flow.
Tanjiro was right behind them, his blade flashing to deflect the massive, slow-moving hands that swept towards the Golems' feet. "The stone is too hard! My blade breaks if I hit the main body!"
"Focus on the joints!" Jin-Woo yelled.
The Golems were distracted, but their physical defenses were immense. It was a slow, agonizing process.
"This is taking too long," Saitama grumbled. He walked over to the first Golem, which was currently engaged in a slow-motion crush attempt on Gojo.
Saitama reached out and placed his hand flat on the Golem's chest. He exerted just enough force—the absolute minimum required to bypass the magical density of the granite.
The Golem didn't explode. Instead, the entire structure of the rock was instantly liquefied beneath his palm, turning the Golem into a massive pile of inert, bubbling sand.
"There. Disabled," Saitama said, brushing the dust off his glove. "Next time, use sand."
Gojo stopped mid-dodge, staring at the pile of goo. "That's not disabling! That's... that's structural failure at the subatomic level! You're the worst teammate ever!"
Jin-Woo, however, looked intrigued. "The method is too destructive, but the result is instantaneous neutralization. Use the same force on the second one, Saitama. We have a time limit."
Saitama sighed and repeated the motion, turning the second Golem into a separate pile of sand.
The second floor was a maze of magical traps. Here, Jin-Woo's strategic mind truly shined.
"Okarun! Traps!" Jin-Woo commanded. "Use your speed to move ahead. If you sense any magical flow that is not a monster, identify it."
Okarun, despite his fear, obeyed. Turbo-Granny's possession kicked in, and he became a panicked streak of motion, zipping ahead. "Laser grid! Pressure plate! Poison dart launcher! They're everywhere!"
"Kazuma!" Tanjiro called out. "You have the highest Luck! Which path is the least lethal?"
Kazuma, still clutching the remnants of his toad tongues, squinted at the two paths ahead. "Uh... the left path has the highest chance of having good loot! So, by the laws of my terrible life, it's probably a guaranteed death trap! We take the right one!"
"Logical deduction through self-deprecating irony. Proceed right," Jin-Woo said, impressed.
The right path was clear of physical traps, but they were immediately confronted by Dark Sorcerers—floating, robed figures that fired bolts of pure shadow energy.
Gojo, rationing his power, engaged them defensively. "I can't use Red or Blue! Too much drain! I'll use my domain expansion... minimally!"
He didn't cast the actual Domain. He merely expanded the concept of Limitless, creating a localized pocket of infinite distance around his body. The Sorcerers' shadow bolts traveled toward him, but simply stopped moving an inch from his face.
"You're stuck in the concept of 'infinity'! Have fun!" Gojo yelled, bored, then turned to Jin-Woo. "Now, the killing blow. I've used less energy than walking."
Jin-Woo deployed Beru. The Ant Monarch appeared in a cloud of intense shadow energy. "Beru. Annihilate the Sorcerers. Use only sufficient force to collapse their magical core. No excessive explosions. Ration the Mana."
Beru, bowing low, emitted a terrible shriek and launched himself at the Sorcerers. The fight was swift, brutal, and perfectly economical. Within seconds, Beru had collapsed the magical cores of all the Sorcerers, and they dropped from the air like dead flies.
They reached the third and final floor—a massive, open arena where the Sentinel Boss awaited them.
It was a nightmare from Jin-Woo's past: a Gatekeeper Knight, similar in power to Igris, but wielding a massive, jagged runic broadsword and protected by an aura of pure, defensive Shadow Magic.
"This is the challenge," Jin-Woo said, his voice grim. "The defenses are too high. Saitama cannot liquefy him without causing a catastrophe. Gojo's Cursed Energy will fail before his defenses do."
The Gatekeeper Knight raised its broadsword, and a wave of concentrated magical energy pulsed outward, creating a debilitating field around them.
"Kazuma, Okarun! Retreat and cover the entrance! Tanjiro, Jin-Woo, Gojo, and Saitama! Focus fire!"
"I need to use my ultimate defense!" Gojo declared, his eyes blazing. He prepared for a full-power Cursed Technique. "Jin-Woo, you get one shot! Make it count!"