This F-Rank Bubble Mage Is Too OP!

Unlike F-Rank dungeons—where most monsters can be dispatched by ordinary humans—E-Rank monsters are far stronger, leaving non-hunters with no hope of defeating them.

Even a single Rotling can overwhelm five people at once. They feel no pain, know no fear, and understand only one thing: to charge forward and devour anything alive.

River had been cutting them down for over an hour now.

They were dead before, but now… now they were nothing more than mangled remains, blown apart into unrecognizable pieces.

River stood amid the scattered corpses, the forest floor littered with torn limbs and black ichor that soaked into the dead soil. The faint stench of rot clung to the air, heavy enough to coat the back of his throat. He let out a slow breath, not from exhaustion but from the simple relief of having a moment to himself.

The fight had not been a quiet one.

The instant he struck down a single Rotling, the sound of its death cry had rippled through the twisted woods like a dinner bell. Within moments, the forest had erupted with movement—nearly a hundred of them swarming from every direction.

River had been ready. He always was.

Bubble Bombs shimmered into existence around him in flawless arcs, their blue light reflecting off his mask. Each one burst with concussive force, sending bodies tumbling and bones shattering. It had taken time—longer than he would have liked—but one by one, the creatures fell until silence returned, broken only by the faint hiss of dissolving monster remains.

The familiar chime of the System echoed in his ears.

[Level Up.]

[Level Up.]

His Status had shifted—Level 20 now. Five unused Stat Points waited for him, but he didn't touch them yet. "I'll handle that when I'm out of here," he murmured, brushing black ichor from his sleeve. In a dungeon like this, pausing to optimize mid-hunt was just asking for trouble.

Still, he couldn't help but sigh. "Two hours of work… and only two levels." His voice carried a faint edge of disappointment. Power came steadily, but never quickly enough for someone with his goals.

After a careful scan of the area to make sure no stragglers lurked nearby, he set off again. His steps were light, deliberate—always listening, always watching.

It wasn't long before distant shouts reached his ears. Through the tangled branches, he spotted a group of Hunters locked in combat with a pack of Rotlings. One of the monsters was noticeably larger than the others—its hide thicker, its movements heavier—but still far from Alpha-tier. Judging by the Hunters' frantic swings and ragged breathing, they were struggling.

River didn't break his stride.

He'd already decided he wasn't in the mood to play the villain twice in one day. Without so much as a glance back, he veered off, searching for another hunting ground where he could work in peace.

The smaller Rotlings weren't worth much individually. Their drops were mostly low-grade materials, common enough that most people ignored them. But River knew better—sell them in bulk, and they could still bring in a decent sum.

Every time a creature fell, he stooped to check for loot. Maybe one in every dozen yielded something tangible, but he didn't mind. His Inventory held ten items—a modest haul, but one that would add up.

The second area he entered didn't have many Rotlings—maybe only a few dozen scattered in small clusters. River dispatched them one by one, his Bubble Bombs bursting through rotting limbs and leathery hides. The dull chime of his System window confirmed each kill, but the reward bar barely moved.

His EXP requirement for the next level had risen again, and compared to the amount he needed, what he'd just earned felt like a glass of water poured into a bucket. Barely worth the effort.

If River wanted to level up even once more, he would have to grind for at least another hour. And it would be harder now—every Rotling pack he cleared meant fewer to find later. By the time he was done, there was a good chance the dungeon's boss would already be dead, claimed by some other group.

He paused, tapping his fingers against his arm as he considered his options.

The Dungeon Boss.

Just thinking about it made his eyes sharpen.

Weak trash mobs gave trash EXP, and he didn't have the luxury of wasting time. But the boss? That was a concentrated jackpot. Defeating it could push him to another Level at once, not to mention the potential loot.

"Hmm… should I?" River muttered to himself, though his feet were already moving in the direction he knew would lead deeper into the dungeon.

If someone else had found the boss first, then… well, he didn't mind doing what he'd already done once today. A kill steal was still a kill.

A bubble shimmered into existence in front of him, wobbling slightly under his weight before it firmed up, its surface catching and distorting the pale light of the dungeon's moon. River bent his knees, then jumped, the bubble springing him forward like a slingshot. Before he hit the ground, another bubble formed ahead, perfectly placed. He landed on it and launched again.

Soon, he was a blur, bouncing from one bubble to the next, vaulting over ruined trees, cracked stone outcroppings, and pits of rotting sludge.

In most dungeons, the boss laired near the center, but River knew better than to assume. There were exceptions—plenty of them. Some bosses hid underground, some perched in the highest cliffs, and some blended into the dungeon's design until the moment they struck.

As he vaulted over a wide swamp, its surface a sluggish, tar-like black, a thought struck him hard enough to make him pause midair.

"This is possible…" His eyes narrowed.

This dungeon didn't just have dead trees and cracked earth. It had these swamps—thick, oily boiling lakes that didn't fit naturally into the terrain.

Why would something like this exist here unless it served a purpose?

In his experience, dungeons rarely wasted features. Every element had intent—whether to hinder, trap, or hide something.

He dropped lightly to the cracked ground beside the swamp and closed his eyes. Mana began to swirl around him in a faint, invisible current. Normally, Mana Gathering was a way to pull energy into himself, to replenish and fortify his reserves. But River had learned to twist its principles, to send his mana out in a fine net, spreading it across the environment like a spider weaving threads.

To others, it was impossible—too much control required, too much risk of losing the delicate balance of output and recall. To River, it was as easy as breathing.

His awareness expanded, a ripple passing across the swamp's thick surface. He "felt" the liquid, the sluggish movement beneath, and the faint currents trailing away. The swamp was connected—no, not just connected. It was a feeder pool to something much larger.

His lips curved faintly.

Opening his eyes, he turned in the direction the mana threads pulled him toward. Somewhere beyond lay a greater body of that black, boiling tar-like liquid… and where such an unnatural formation existed, a guardian or master often waited.

He didn't hesitate. Another bubble formed beneath his feet, and he launched himself toward the horizon, the faint suction of swamp air rushing past his ears. The terrain blurred beneath him—dead ground giving way to more swamp, then black ground, then swamp again.

Twenty minutes later, he found it.

A vast lake stretched before him, far wider than any of the smaller swamps. The air above it was thick and foul, every breath carrying a chemical tang that stung his throat. The black liquid shifted slowly, as though breathing, and faint ripples traced across its surface despite the absence of wind.

This wasn't just a lake. It was alive.

River's hand drifted toward one of his Bubble Bombs, but he didn't throw it. Not yet.

He extended his senses again, mana threads sinking into the lake's depths. Something stirred far below—something massive, probaly one or two story tall, slow, and patient. It was motionless now, but that stillness was deceptive, the way a predator could seem like a shadow until it struck.

His pulse picked up—not from fear, but from anticipation.

This was it. The Dungeon Boss.

A Rotling variant, if his guess was right. Something adapted to the swamp, probably stronger, faster, and far more dangerous than its land-bound kin. And judging by the sheer mana signature radiating from beneath the surface, killing it wouldn't just be rewarding—it would be spectacular.

River allowed himself a faint smile.

Before attacking the Dungeon Boss lurking within the swamp, River decided to finally allocate his Status Points. Initially, he had planned to use them once he was outside, but now that he stood face-to-face with the boss, boosting his stats immediately would give him the extra edge he needed to bring it down faster.

This wasn't his first time facing a monster of this type. Back when he was still one of the Last Hunters, he had fought countless undead abominations—some towering higher than skyscrapers. Compared to those titans, the creature lurking in this lake was nothing more than a baby.