Doppelgangers
Doppelgangers.
That was what I called the monsters of the Seoraksan Dungeon.
The reason was simple enough. Their appearance might have been nothing more than black oil gathered into the shape of a slime, but their means of attack, their habits, their techniques, and the sheer volume of their power were all calibrated to the strongest person inside — and they copied those things almost perfectly. About ninety-seven percent, give or take.
Which meant, put another way, that they could reproduce my techniques — the Heavenly Demon Divine Art included — to roughly ninety-seven percent fidelity, even if they couldn't quite manage a perfect copy.
— BOOM!! BOOM!! BOOM!!
White Nights came screaming in from every direction, vicious and relentless.
Tch. This is exactly why I hate these bastards.
The fact that they mirrored my attack patterns and habits meant that knowing myself made them easy to counter — but only for a little while. Before long, even those counters would get copied too.
First Form
— Thud-thud-thud
The veins along Cheon Seong's arms bulged and burst under the crushing pressure.
White Night
The strongest White Night he could possibly unleash swallowed the doppelgangers' own White Nights whole and smashed them apart.
Pop.
— Gulp
He topped off the spent mana with a potion Beatrice had prepared for him. Whether she'd put extra care into brewing it or not, the stuff worked better than the potions he'd used while practicing teleportation magic — his mana recovered in no time.
— Whoosh
The moment his mana was restored, he blinked to a spot he'd marked in advance and struck at the doppelgangers from behind.
Second Form
Black Night
Ink seeped into bodies that already looked like black paint, and the darkness swept them away.
— Hah… hah… hah…
Those fleeting seconds while they were swallowed by Black Night were the only chance he had to catch his breath.
Second Form
Black Night · Black Night Sky
Black Night Sky — the follow-up technique to Black Night. The dark mana that had spread through them gathered toward the heavens and pinned their feet as if a high-tier gravity spell had slammed down on them.
"Now get the hell out of my way!!"
— CRUNCH!
He lunged at the immobilized creatures, aiming for the one thing that mattered — a core the size of a small marble, sitting roughly where a human heart would be, nestled in bodies that were otherwise nothing but empty darkness.
— Shlurrrk
Stripped of their cores, the doppelgangers lost all ability to hold their shape. They poured onto the floor and died.
— Gurgle-gurgle-gurgle
"Hah… hah… Shit. There's a disgusting number of them."
The doppelgangers he'd already put down numbered in the hundreds, easy. And waiting to greet him on the other side were hundreds more.
At this point they weren't doppelgangers — they were maggots. Maggots clustered by the dozens in a single spot. Hundreds of them packed so densely that the already dark cave looked like a bottomless cliff where no light could ever reach.
"…Wait. That one looks off…"
In the heart of that darkness, a single tiny red light was glowing. At the very back of the horde stood a doppelganger with features that set it apart from all the rest — and Cheon Seong's eyes locked onto it.
"No way…?"
An endless tide of doppelgangers. And among them, one solitary creature with distinctive traits, looking for all the world as though the other black organisms were protecting it.
"You're the main body!"
Third Form
Moonlit Night
A night of the bright full moon unfolded — light of White Night and darkness of Black Night fused into one. And that night came crashing down upon the doppelgangers.
— SHWOOOOOOM!!!
— BOOM—!!
The doppelgangers were blasted aside by Moonlit Night. Cheon Seong tore through the scattering swarm at full speed and closed the distance on the red-glowing one.
"So it really is you."
Up close, he could tell. This one was connected to all the others out front.
Without hesitation, he drove a dark-mana-wreathed arm straight into the red light — the spot that, on a human, would have been an eye.
— Shlurk!
The moment it was struck, the other doppelgangers came charging even as their bodies melted and died around them. That only confirmed it. He punched clean through the creature and ripped out whatever his hand closed around.
"Time to die, you parasitic piece of shit."
— SHLURRRRRK!!!
The instant he pulled it free, every last doppelganger liquefied and flooded the floor.
— Squelch
"Hah, shit. Disgusting as hell."
The melted filth clinging to his boots made his stomach turn.
"I've wasted too much time."
Roughly an hour had passed since he'd entered the dungeon, and he'd spent far too long stuck in one place.
"I need to pick up the pace."
Still — now that he knew the main bodies existed separately, he broke into a run.
— Whoosh—!
A single blue slash came screaming toward him as he charged forward.
— BOOM!!
He twisted mid-sprint and drove a fist wrapped in dark mana into the slash, knocking it aside.
— Sizzle-crackle
The recoil between the slash and his fist shoved his body backward.
I didn't sense it coming…
Ever since he'd learned spatial magic, he'd grown strong enough to casually beat Mid-rank opponents so long as the matchup favored him. Mentally drained as he was from the nonstop fighting with the doppelgangers ahead, his presence detection had still been running at full capacity the entire time — and yet he hadn't sensed that slash until it entered his field of vision.
— Step. Step. Step.
"Huuh…? Who…?"
From the direction the slash had come, a young man emerged — sky-blue hair, androgynous features.
"…That's my line. Who the hell are you?"
"Hmm…? Usually… doesn't the person who asks first answer first…?"
Something about him seemed a little — no, a lot — spaced out.
"You attacked first, so etiquette says you answer first, doesn't it?"
A stupid question, really. In a dungeon, outside common sense and courtesy meant nothing. The only thing you could trust was yourself. Even companions who'd entered alongside you had to be treated with caution. A dungeon was a place cut off from the outside world — crawling with monsters, laced with unknown traps — which made covering up a crime absurdly easy. Even outside, where nothing was sealed off, plenty of crimes went buried. In a dungeon, severed from the world and where disposing of a corpse was trivial, there was nothing more to say.
Anyone with half a brain would have understood that what he'd said wasn't really about manners — it was a warning. This vacant-looking kid, however, was not that anyone.
"Hmm… you've got a point. I'm Si-yun."
But Cheon Seong focused less on the kid's vacant willingness to offer up his identity and more on the name itself. It could have been a lie, of course — but the still-youthful face, the sky-blue hair, and a slash that had slipped past his detection… everything pointed to one person.
"Si-yun? Don't tell me — Seol Si-yun?"
"Huh…? You know me…?"
Know him? He'd heard that name so many times before the regression he was sick of it.
Seol Si-yun, the Sword God.
Before the regression, he'd been called the Sword God — known across the world as the strongest man alive — and he'd been the constant measuring stick against which a half-wit like Cheon Seong was compared. Always unfavorably, of course.
Yoo Hwa-young might have been the first to kill a Celestial, but the one who'd killed the most before the regression was Seol Si-yun. Five Celestials, by his hand alone. Of the ten that all of humanity had managed to bring down combined, he'd taken half by himself. A monster. To the traitors who'd betrayed humanity and sided with the Celestials, he'd been nothing less than the god of death itself.
That was Seol Si-yun.
"Hey, are you going to answer or not?"
Seol Si-yun prodded him while he was lost in thought.
"I know you well enough. Who wouldn't know the Sword Saint's son?"
"Hmm… is that so?"
"So why did the Sword Saint's son attack me?"
He focused the oppressive weight of his dark mana on Seol Si-yun as he asked. Before the regression, Si-yun might have been stronger — but not now. He couldn't gauge the kid's exact skill level, but the doppelgangers out front had already answered the question of who was stronger. Every technique those creatures had used had been his. Doppelgangers copied the power and techniques of the strongest person who'd entered the dungeon. The fact that they'd been using his techniques meant that, for now at least, he was stronger than Seol Si-yun.
He wouldn't kill him. There was no reason to — and the kid would be an invaluable asset in the war against the Celestials. But not killing him was one thing. If there was even a shred of malice in that attack, Cheon Seong would shatter one of his limbs.
The pressure he was radiating would have driven even a Lower-rank hero to their knees. Seol Si-yun's face, however, remained utterly serene. And then the words that came out of the kid's mouth reminded him that there was one more thing the name Seol Si-yun stood for.
"I just… the monsters were using… weird martial arts and magic, so… I was looking around to see if there was some strong person they were copying or drawing from… and I felt a strong presence, so I attacked."
Life sparked in irises that had been nothing but hazy fog.
Seol Si-yun, the Sword God. The strongest man in the world — and a battle-crazed maniac who lived for fights against the powerful. That, too, was Seol Si-yun.
"You're strong. You look fun. So fight me."
Mana rippled along Seol Si-yun's blade, coating the steel.
Aura.
The mark of someone who had stepped into the Mid rank — Aura bloomed along Seol Si-yun's sword.
"More fun than the monsters. So… here I come."
— Whoooom!
Seol Si-yun's blade grazed past his hair. Cheon Seong slammed a foot into the ground and threw himself backward.
Fast.
The moment he retreated, Seol Si-yun's attacks flowed into the next as naturally as a dance, pouring down on him without pause. The problem was that they still looked rough around the edges — like the kid was using him as a practice dummy for techniques he hadn't fully polished yet. And that was pissing him off.
"You little shit—!"
First Form
— Tremble-tremble-tremble
Cheon Seong's arms shook violently under the crushing pressure of the dark mana. A clear sign he was forcing a technique past his limits.
"—!"
Seol Si-yun must have sensed the danger too — he put distance between them in a flash. But now it was Cheon Seong's turn to land a hit.
White Night
— Rumble-rumble-rumble — the ground quaked as a pure white day expanded its domain through a dungeon that had known only darkness. White Night's light flooded every corner of the cavern. The dungeon itself began to crack; the floor, unable to endure, split apart.
But it wasn't over. He'd seen Seol Si-yun mitigate the worst of White Night's damage at the last second.
So he attacked immediately— Whoom!
— SKANG!!
Dark crimson blood sprayed across the dungeon floor.
"Shit! What the hell is wrong with these monsters!!"
— Crackle-ZZZAP!
— Sizzle-sizzle-sizzle
High-voltage lightning vaporized the doppelgangers on contact.
It was Cheon Yu-seong.
He was currently pushing toward a secret passage he knew about, trying to reach one of the doppelgangers' main bodies.
— Gurgle-gurgle!!
"Ugh! Get the hell off me, you disgusting bastards!!"
— ZZAP! Crackle-ZZZAP!!
He poured powerful lightning in every direction, clearing the doppelgangers that kept coming at him.
Gurgle-gurgle!
But even through that high-voltage storm, one doppelganger survived — and drove a fist at him wrapped in something. Cheon Yu-seong tried to unleash another burst of lightning, but it fizzled. He kicked off the ground and threw himself backward instead.
"Hah… hah… Shit. Lightning God's already at its limit."
Lightning God — Cheon Yu-seong's unique ability. It let him wield high-voltage lightning, but the mana cost was brutal. The number of doppelgangers he'd killed since entering the dungeon already ran into the hundreds. And in all that time, he hadn't managed to take down a single main body.
All because of how strong these things were.
"Why the hell are they this strong!! And what even are those techniques!!"
As a transmigrator, Cheon Yu-seong knew the Seoraksan Dungeon's characteristics well enough — the so-called Doppelganger Dungeon. He knew their strength scaled to the strongest person who'd entered.
"I came straight here the second it opened — so who the hell got in before me!!"
Pop! — Gulp
He downed one of the Highest-grade mana recovery potions he'd brought for exactly this situation and activated his unique ability again — Lightning God.
— Sizzle-sizzle-sizzle
The doppelgangers were helpless before Lightning God's bolts. After forcing down two more mana recovery potions, Cheon Yu-seong finally dropped a main body and collapsed onto the floor.
— Squelch-squelch
"Shit, this is revolting. Would it kill them to just vanish when they die? Every last one of these things is completely fucked."
The ground fouled with doppelganger corpses turned his stomach — but an hour of nonstop combat had a way of making even a floor coated in disgusting filth look like a place worth sitting down.
"Haaah!! Goddammit, I've still got four more of these things to kill!!"
Cheon Yu-seong's rage — and a thread of despair — echoed through the dungeon.