“Mhm… what is this?”

Aestrea’s eyes flicked to the ground, spotting something shiny beneath the lizard’s massive body.

His fingers twitched.

Thud!

He kicked the lizard’s carcass with a sharp snap of his boot, sending it flying a few meters to the side.

The moment the body moved, he crouched down before picking up a small object, and as his hand closed around it, a slight shimmer caught his eye.

It was a key.

He raised an eyebrow.

“A key?” he muttered, turning it over in his hand.

He focused for a moment, activating his scan ability.

“Scan.”

[Name: Red Slayer’s Boss Key]

[Effects: Opens the door to the boss room of the “Red Slayer Dungeon”.]

[Details: If you throw this key into the lava in the volcano, a hidden stairway will appear, leading towards the boss’s room.]

Aestrea let out a low chuckle.

“Ah! So there was something about the volcano,” he said, shaking his head in disbelief.

He pocketed the key and glanced around.

Without wasting a moment, he spun around and darted towards the volcano’s edge.

Swoop!

The ground shook slightly beneath his feet as he sprinted across the cracked earth, heading toward the giant hole in the mountain.

As he reached the edge, he jumped forward, landing on the stone ledge just beside the volcano’s mouth.

The heat hit him like a wall, but his aura shielded him.

Then, he held the key in front of him before tossing it into the bubbling lava.

SPLASH!

The key sank into the lava, disappearing into the molten rock with a hiss.

For a moment, nothing happened.

Then, the ground trembled.

RUMBLE…

A loud grinding noise came from beneath the volcano, like gears shifting.

A deep crack formed along the base of the mountain, and stone walls began to rise from the earth, slowly revealing a hidden stairway that led down into the dark.

Aestrea grinned.

“Perfect.”

He stepped forward and descended the staircase.

The air grew hotter as he moved, but the small barrier around the stairs kept the lava from flowing up.

At the bottom, he entered a strange cave.

Red crystals sparkled everywhere, reflecting the dim light from the lava pools that dotted the space. The lava was held back by large rocks, barely contained but not spilling.

“Scan.”

[Name: Red Magic Crystal]

[Effects: Can be used as a mana recovering potion if you absorb mana from the crystal.]

[Details: It’s an excellent material for weapon refining, and has the ability to absorb mana from its surroundings.]

“Hah? This can be useful…”

Upon seeing the abundance of the crystal inside the cave, Aestrea’s eyes immediately curled up like crescent moons.

He smirked and then gripped his scythe tightly, swinging it at the nearest crystal.

Crack!

The crystal shattered into pieces, but to his surprise, it didn’t break apart completely. The large shard stayed mostly intact.

Aestrea quickly used his magic.

『 Storage 』

A small purple portal opened in front of him, and with a flick of his wrist, he tossed the crystal inside.

The portal snapped shut with a faint pop.

He then glanced over at another crystal, and upon seeing it, his lips formed an extremely greedy smile.

Swip!

Another swing of his scythe.

Crack!

The crystal broke cleanly, and Aestrea tossed that one in too.

‘Lumi’s skills really are useful…’

He smiled inwardly as he continued swinging his scythe.

It took him about twenty minutes to mine every single crystal, however, it was a fantastic harvest for Aestrea.

Finally, he stood back, wiping his hands off and closing the storage portal.

Aestrea turned around, eyes narrowing.

At the far end of the cave were massive red doors, covered in glowing purple symbols.

They pulsed softly, as if alive, the air around them humming with energy.

“Mhm…” Aestrea hummed to himself, walking slowly toward the doors.

He stretched out his mana, trying to feel through the barrier.

But it didn’t work.

“Tsk… this is going to be a bit of a problem.”

He clicked his tongue in frustration.

His mana unfortunately couldn’t get through the door, so he couldn’t see what kind of demon beast was behind it..

He paced back and forth for a moment, wondering what to do next.

Then, a thought crossed his mind.

“System, change the Scan’s setting to show the characteristics of a boss monster.”

[Done.]

Aestrea let out a long breath, relieved.

“Phew~… didn’t think that would work.”

Without further ado, Aestrea took a step closer to the door.

Then—

BAAAM!

He kicked the giant doors wide open. Dust swirled into the air as the massive doors slammed against the walls, revealing a gigantic room.

The space was enormous, big enough to fit more than ten average-sized houses.

“Dammit… what kind of boss monster needs a boss room this big?” Aestrea gripped his scythe tightly as he looked around cautiously.

[Ding! Cold-Blooded [S-] trait found!]

Aestrea froze slightly, glancing at the panel.

“Huh…? Ah, the trait I gained when I was fighting against the Archdemon. Was it deactivated for some reason?”

[Indeed. Because the user already possessed a similar talent, the trait was temporarily deactivated.]

Aestrea tilted his head.

“Huh. Didn’t know that could happen. After all, the Cold-Blooded trait’s rank is much higher than my Calm Mind talent.”

[Would you like to fuse the trait with your talent—Calm Mind [A-]?]

Aestrea’s eyes flicked back and forth as he glanced around the room, trying to stay aware of any movement.

“Ah, you can do that?” he muttered, still wary, his grip on the scythe tightening as he continued scanning the area.

“Why are you suddenly so chatty, anyway?” he asked suspiciously.

The system had been strangely much more active than usual since the quest began.

[…I am currently under the host’s service, as you are carrying out a quest that stabilizes the strings of fate.]

Aestrea’s face twitched at his words.

“So if I weren’t doing this quest, you’d be silent?”

[…]

Noticing the system’s silence, Aestrea clicked his tongue in frustration.

“Tsk. Just fuse it.”

[Fusing…]

[Fusion complete! You have gained the Passive Talent—”Moon’s Serenity [SS]”!]

[Moon’s Serenity [SS]: A state of perfect composure, where emotional distractions melt away and the mind remains as calm and focused as the still moon.]

Immediately, Aestrea’s twitching face changed, turned a shade colder.

He merely glanced at the panel, and despite wanting to frown, his facial muscles didn’t move a single inch.

“Really…? Moon’s Serenity?”

He asked the system.

[…]

However, the system remained silent.

“I’m starting to think that this system was given to me by the Goddess of the Moon.” He sighed and muttered under his breath.

But before he could think further, something caught his attention.

The boss still hadn’t appeared.

Somehow.

Seeing this, Aestrea raised his hand, pointing his fingers forward.

『 Minor Frost Explosion! (✦ 5th-level Spell ✦) 』

A small, faint blue orb materialized at his fingertips.

The moment it appeared, he flicked his fingers.

BAAM!

The air snapped cold as the ball of energy exploded. Ice shards sprayed in every direction, crashing against the floor with a sharp CRACK.

For a split second, everything went still.

Then—

RUMBLE!

The ground beneath him shook violently, cracks splitting across the stone floor as the walls trembled.

Aestrea’s eyes immediately narrowed, scanning for the source.

BAAM!

The rock walls on the far side of the room exploded outward, sending chunks of debris flying as a massive figure stepped through.

“Who dares to invade my territory?!”

A rough and terrifying voice escaped the monster’s mouth.

Aestrea didn’t flinch.

His eyes narrowed as he analyzed the boss.

The figure was massive, standing tall with a humanoid shape. Its skin was a deep, blood-red, veins pulsing underneath like a living flame.

Its body was covered in dark, intimidating armor, but the helmet was missing, revealing the blazing fury in its eyes.

On its back, a massive red sword hung in its scabbard, gleaming with an ominous glow.

“…Scan.”

The panel appeared instantly in his vision.

[Name: Red Slayer

Health: 100%

Rank: S++

Affinities: Azure Fire (Evolved Fire Element)

✦ [Skills] ✦

[1] Crimson Cleave [S++] ➤ Active Skill – A devastating horizontal slash with his massive red sword, dealing heavy area-of-effect damage.

[2] Inferno Strike [S] ➤ Active Skill – Charges up a fiery attack, targeting multiple enemies in a straight line, dealing fire damage.

[3] Crimson Armor [SS+] ➤ Passive Skill – Grants a powerful defense boost, reducing incoming damage by 40%.

[4] Titan’s Wrath [SS+] ➤ Ultimate Skill – A final desperate attack that unleashes a massive explosion of fiery energy, dealing catastrophic damage to all enemies in range.

✦ [Weaknesses] ✦

Ice Magic – Deals significantly more damage to Red Slayer, slowing his movements and reducing his attack speed.

Mind Magic – The Red Slayer is mentally weak, which causes Mind Magic to be extremely effective against him.]

Seeing this, Aestrea’s eyes widened in curiosity.

He had never seen a monster with an evolved element before, and now he was wondering what kind of evolution his ice element could have.

“Shit… this is going to be tough.”

He grabbed the hilt of his scythe.

‘Increase mana output to 9 times.’

He immediately acted; the only reason he didn’t put it to the maximum was that he wouldn’t be able to hold it for a long time.

『 Judgement Eye (✦ S+ Level Skill ✦) 』

『 Wound Aggravation 』

『 Curse Mark 』

Aestrea didn’t waste any time and quickly applied all the spells used to weaken or analyze the boss monster in front of him.

Fwip!

Suddenly, the Red Slayer lifted up his sword.

At that instant, Aestrea was already in motion, a step to the side as the beast swung a devastating Crimson Cleave—a massive horizontal slash.

The blade tore through the air with a sharp whistle, the ground itself shaking as the blade crashed through the space where Aestrea had just been standing.

SWOOSH!

He ducked and rolled, narrowly missing the red-hot edge of the blade, feeling the heat singe the air around him.

He didn’t wait for the monster to recover.

Instead, he thrust his hand forward, mana gathering on it.

『 Ice Series: Frost Spikes! (✦ 3rd-level Spell ✦) 』

In an instant, sharp, jagged spikes of ice shot from the ground beneath the Red Slayer’s feet. The spikes shot upward with deadly speed, aiming for his exposed legs.

SHING!

One spike pierced through the Red Slayer’s shin, causing him to grunt in pain.

Blood sprayed from the wound, mixing with the ice shards.

The Red Slayer growled slightly, while Aestrea darted to the side, maintaining his distance while keeping a close watch on his every move.

Then, the massive figure took a step forward, raising his sword high, probably preparing for another Crimson Cleave.

But Aestrea wasn’t waiting for it.

『 Ice Wall! (✦ 3rd-level Spell ✦) 』

He clenched his fist and slammed it into the ground, summoning a thick, icy Ice Wall that shot up between them, blocking the incoming attack.

The sword smashed into the wall, cracking the wall into countless pieces, the impact sending vibrations through the floor.

Aestrea quickly followed up, raising his hand.

『 Frost Explosion! (✦ 6th-level Spell ✦) 』

A small, blue sphere formed at his fingertips, and he flicked it toward the Red Slayer’s torso.

BAAAM!

The orb burst on impact, sending a shockwave of cold air.

The Red Slayer staggered back, his armor cracking as the ice spread across his body, freezing a portion of his arm and part of his chest.

SHRIEK!

The beast roared in fury, his body glowing with a strange blue fiery energy as he swung his sword in retaliation.

“Tsk.”

『 Ice Series: Glacial Dash! (✦ 5th-level Spell ✦) 』

Aestrea quickly moved to the side, evading the wide, fiery arc of the sword.

SWOOSH!

The blade scraped the ground, leaving a trail of molten rock as it missed by mere inches.

Aestrea’s eyes glowed slightly as he looked at the boss.

The Red Slayer was recovering fast, the flames surrounding his body intensifying.

『 Inferno Strike! 』

The Red Slayer’s sword began to glow with intense heat as he prepared a fiery line attack. Aestrea could feel the heat from here, and he acted instantly.

With a quick step back, Aestrea slammed his palm into the ground once again.

『 Ice Series: Frost Chains! (✦ 5th-level Spell ✦) 』

Chains of ice shot out from the ground, wrapping around the Red Slayer’s legs and arms. The chains tightened, pulling him down as he tried to break free.

He let out a roar of rage, thrashing against the ice, but it held firm.

SNAP!

The chains tightened once more, causing him to stagger.

“…Perfect.”

However, before Aestrea could act again…

ROAAARR!

An azure flame enveloped the Red Slayer’s body, melting the ice chains in the fraction of a second.

“Dammit!”

Aestrea lifted his scythe,

『 Ice Series: Frost Crash! (✦ 6th-level Spell ✦) 』

A massive chunk of ice materialized above the Red Slayer’s head and smashed down, shattering on impact.

Ice shards exploded outward, cutting into the Red Slayer’s side. His blood splattered, a deep crimson against the white ice, but he didn’t slow down.

He spun around, his sword raised high, and swung it downward, aiming to cleave Aestrea in two.

CRASH!

Swooosh!

Aestrea dodged to the side just in time, feeling the wind of the massive swing brush against him.

The force of the blow caused the ground beneath them to crack, pieces of stone flying in every direction.

RUMBLE!

Aestrea rolled to his feet, his chest heaving, but his eyes were locked on the Red Slayer.

Another incoming attack!

『 Shield Series: Winter’s Barrier! (✦ 6th-level Spell ✦) 』

BAAM!

The huge sword was slammed against the pentagram barrier, however, it didn’t break in a single hit.

Noticing this, the Red Slayer’s movements became more frenetic!

BAAM!

The Red Slayer’s next strike slammed into the barrier, but it held, the ice cracking slightly but staying intact.

Seeing this, Aestrea took a moment to catch his breath, however, he knew that the next hit was probably going to break this barrier of his.

ROAARRR!

The Red Slayer’s sword was enveloped with blue flames as he swung down at Aestrea’s barrier with full force.

Immediately, Aestrea’s instincts kicked in, as he jumped out of the way.

BOOOM!

CRACK!

The shield shattered instantly, the impact causing the leaping Aestrea to fly a few meters away before rolling onto the ground.

“Pftu—!”

Aestrea spat blood on the ground.

Then, he stuck his scythe in the ground before looking at the boss monster.

“I guess it’s finally time to test a new spell…”

Source: Webnovel.com, updated by NovelKeep