"Hmm?"
On a mountain road over a dozen kilometers from Shinjin Lake, Rozen—still gripping Galatine—suddenly sensed something and turned his gaze toward the lake.
Through his Wise Eye, he could clearly perceive the vast magical energy that had been suppressed within Shinjin Lake now erupting violently.
Then, like locusts or an ant swarm, countless spiritual energies surged outward, spreading in all directions.
"That is..."
Rozen's brow furrowed deeply.
His opponents, however, were not so kind as to let this distraction slide.
"ROOOAR!"
"ROOOAR!"
The two remaining black wyverns roared as they dove toward him, their bloodlust saturating the air.
"BOOM!"
Rozen's wyvern charged from the side, slamming into one of the black wyverns with a heavy thud. The two beasts crashed into the mountainside, locked in a furious struggle amidst the swirling dust.
The remaining black wyvern swooped directly at Rozen, its claws outstretched as if to sever his head.
Unfortunately for it—
"Splurt!"
A flash of sword light cut through the air. Instead of reaching Rozen, the wyvern's claws were met with Caladbolg, wreathed in solar flames. Its scales shattered, and one claw was nearly severed entirely.
"ROOOAR—!"
The black wyvern howled in agony, instinctively pulling back.
Rozen watched it coldly, his eyes glinting.
The reason? Though Galatine had struck true, the moment it made contact, the solar flames coating the blade were nullified by the black aurora. Only the sword's physical sharpness had inflicted damage.
"As I thought, any attack using magical energy is completely ineffective."
The black wyvern itself wasn't particularly strong—its power was roughly on par with Rozen's wyvern. The real problem was that foreign erosion, which had dragged the battle out this long.
With an ability that nullified all supernatural attacks, even if Rozen summoned a Beast Vassal, it likely wouldn't be able to harm the black wyvern.
Only direct physical attacks would work.
Beast Vassals were aggregates of magical energy without physical form. Unless they possessed special properties, they wouldn't be able to bypass the black wyvern's defenses.
Fortunately, fully materialized familiars didn't have this issue. Since they were entirely physical, as long as they didn't rely on magical attacks, they could still deal damage.
So then—
"Shall I intervene?"
Artoria [Alter]'s voice echoed in Rozen's mind.
"Senpai, I can fight too."
Mash's resolute tone followed.
"My poison should also be effective."
Serenity added her input.
"...My flames probably won't work on those wyverns."
Jeanne [Alter] sounded distinctly displeased.
Among the four Servants, while Jeanne [Alter] relied more on her Noble Phantasm's power, the other three's abilities should still be effective against the wyverns.
Especially Artoria [Alter] and Mash—both were masters of close combat. Against enemies that nullified magic, they would be invaluable assets.
However—
"Opponents of this level don't warrant your involvement."
Rozen didn't consider the black wyverns particularly troublesome. At most, their foreign erosion ability was an annoyance.
And besides—
"Not all abilities are ineffective against them."
His gaze shifted to the side.
There, Yukina was locked in fierce combat with the last wyvern.
"Haaah!"
Augmented by physical enhancement spells, Yukina danced through the battlefield, her spear flashing like silver lightning as she clashed with the black wyvern.
"Splurt!"
The wyvern's flank was sliced open, scales shattering one after another.
"Boom!"
The shaft of her spear struck like a hammer, sending the beast crashing back.
The Mechanical Demon-Purging Assault Spear Mark Seven amplified spiritual energy. Wielding this divine armament, Yukina's spiritual power was enhanced, and the potency of her spells increased, elevating her speed and offensive power far beyond the black wyvern's.
"ROOOAR!"
The wyvern seemed enraged. With a roar, the black aurora of foreign erosion enveloped its body, attempting to negate the spear's power.
Yet—
"Sekkaro!"
Instead of retreating, Yukina pressed forward. The tip of her spear gleamed as an intricate magic circle materialized, rapidly multiplying and interlocking into a beautiful, arcane pattern.
The ancient ritual—Divine Oscillation Wave Drive—capable of severing all barriers and annihilating any magical energy.
This power bore striking similarities to the foreign erosion.
In other words, they could cancel each other out.
"Splurt!"
With a silver flash of Sekkaro, the black aurora surrounding the wyvern vanished.
The Mechanical Demon-Purging Assault Spear Mark Seven, said to be capable of slaying even Primogenitors, was the perfect counter to the foreign erosion.
A testament to its might.
"Haaah!"
Yukina didn't waste the opportunity. Her spear shot forth like a beam of light.
"Boom!"
The silver spear pierced the black wyvern's heart, pinning it against the cliffside.
Yukina had felled one of the black wyverns.
"ROOOAR!"
At the same time, Rozen's wyvern seized the moment in its own battle, tearing through half of its opponent's skull with a triumphant roar.
As for Rozen—
"Thud..."
The last black wyvern collapsed before him.
Its body was riddled with gruesome wounds.
Rozen stood calmly as Caladbolg dissolved into embers.
All three black wyverns had been slain. None remained.
"Senpai."
Yukina hurried over.
"Are you alright?"
Rozen asked.
"I'm fine." She shook her head, but her expression was grave. "Senpai... I have a bad feeling."
It seemed her heightened spiritual sensitivity had picked up on something.
"Your intuition is correct." Rozen turned his gaze back toward Shinjin Lake. "Something unpleasant is coming."
Yukina held her breath, stepping silently to his side as they both stared at the distant lake.
There, something like a dark cloud was expanding, spreading in all directions.
Including toward them.
And soon, their enemies appeared.
A horde of monsters.
Each roughly three to four meters long, with heads resembling wasps, serpentine torsos, wings like pterosaurs, compound eyes, and long, whip-like tails. They bore the outline of organic lifeforms, yet their texture was eerily artificial.
Like locusts, they swarmed forward in a grotesque tide.
"What... are those?"
Yukina gasped in shock.
Rozen, however, kept his eyes fixed not just on the monsters—but beyond them, toward Shinjin Lake itself.
"Just what is happening over there?"
He had a feeling things had just become far more troublesome than anticipated.