Since the portraits had chosen to cooperate and open the path, Lewis didn't mind showing a bit of goodwill in return.
"Thank you, professors, for trusting us. Don't worry—we won't misuse this power."
With that, he led the two girls through the doorway.
After another long passage, the three finally arrived at the legendary underground cavern.
It was a vast natural cave, its terrain rugged but its pathways wide—likely because the goblins had once tunneled through here the old-fashioned way, expanding the main routes as they advanced.
Perhaps that was the only good thing they had ever done.
Despite being underground, cracks in the ceiling allowed faint moonlight to filter in. During the day, sunlight likely reached this place as well.
Combined with underground water sources, the cavern supported moss, ferns, and even small patches of flowers and trees.
As they walked, they passed scattered bones.
Most were smaller than human—goblin remains.
But some were far larger.
Trolls.
There were very few human skeletons.
These were the remnants of the goblin army—and their monstrous allies.
After about ten minutes of winding through the cavern, they reached the final gate.
Two five-meter-tall giant golems stood guard before it.
The moment the trio approached, the constructs activated, raising their massive four-meter swords and advancing.
If they had possessed the Keeper's power, they could have commanded the golems to stand down.
But they hadn't come as inheritors.
They had broken in.
So they had to fight.
Fortunately—
After dealing with one before, two more weren't a problem.
Lewis transformed into his Chimera form once again, alternating between lightning breath and acid breath.
It took around twenty minutes—
But the giants eventually fell.
As they collapsed, the ancient magic within their blades activated the runes on the gate.
The door opened.
Beyond it lay—
The sealed vault.
Calling it a "vault" was generous.
It was a barren, massive cavern.
The original bridges and suspended structures had been destroyed long ago.
Now—
It was stark.
Minimal.
The walls and ground were covered in intricate magical runes.
At the center floated a complex metallic sphere, woven from goblin-crafted metal.
Inside—
A mass of glowing white energy.
But beneath that light—
Dark red and black waves churned.
Even from a distance, the three could feel its violent, unstable power.
Lewis narrowed his eyes.
It reminded him of something—
The corrupted Grail.
All the world's evils.
This—
Was the power Isidora Morganach had gathered.
And Lewis had been right.
Leaving this here—
Was like burying a ticking bomb.
Only those with ancient magic could control it.
And even they—
Could only seal it.
The four Keepers had failed to destroy it.
The previous Keeper—the transfer student—had also failed.
All they could do—
Was contain it.
But now?
There were no Keepers.
If something went wrong—
Who could stop it?
Lewis's thoughts turned.
Emotion-born magic wasn't limited to wizards.
It also gave rise to magical creatures.
This was already a known principle in magical zoology.
Creatures like boggarts, ghouls, and others—
Were often born from residual magical energy left by human activity.
At the extreme—
Poltergeists.
They manifested in places like schools, where emotions ran high.
Suppressed frustration.
The desire for chaos.
The urge to break free.
All of it gave birth to beings like Peeves.
And now—
This mass of condensed negative emotion…
If it leaked—
What would be born?
A dark entity?
Something far worse?
And if the seal broke completely—
Would Hogwarts become a magical Chernobyl?
Would every wizard nearby be corrupted?
Or worse—
Would the explosion of magic turn the entire castle into a floating city?
Lewis narrowed his eyes.
"Hogwarts isn't becoming a floating city without me."
"This… needs to be handled."
Hermione's voice trembled.
"L-Lewis… can this even be used?"
She wiped cold sweat from her brow.
Even standing near it felt suffocating.
"I think… we should just leave it sealed."
"That's not an option," Lewis said firmly. "We can't leave something like this under Hogwarts."
The conviction in his voice stunned both girls.
Ciri raised a brow. "You're serious?"
She knew him well.
At his core, Lewis wasn't selfless.
He helped others—but only when it didn't endanger himself.
"…Since when do I joke about things like this?" he replied, giving her a slightly wounded look.
Ciri hesitated.
…Had she misjudged him?
Was he actually… a better person than she thought?
Hermione, on the other hand, looked both relieved and worried.
"Lewis… what are you going to do? If it's too dangerous, we can tell Dumbledore—"
Lewis shook his head as he walked forward.
"Don't rely on Dumbledore. He's not omnipotent."
"This problem… only I can solve."
He stopped beneath the seal.
At this distance, the leaking malice was overwhelming.
Even a small trace could drive a normal person insane.
Only Lewis's powerful mind and psionic defenses kept him unaffected.
"To turn negative emotions into positive ones… to transform malice into goodwill… ordinary magic isn't enough."
"Arcane magic isn't suited for this."
"But that's fine."
He opened his arms.
"I have something else."
"The power of nature."
"Let nature itself cleanse this corruption."
He closed his eyes.
And began.
"Command Plants."
"Revitalize."
"Greater Resistance."
"Healing Spirit."
"Nature's Barrier."
"Nature's Purification."
"Plant Growth."
Spell after spell poured forth.
His energy drained rapidly.
But the surrounding natural power surged.
Then—
The cavern ceiling cracked.
Not collapsing—
But opening.
Massive roots burst through the stone, descending and wrapping around the seal.
Below, grass and flowers erupted from the ground.
Towering oak trees grew in seconds, encircling the base.
Vines spiraled upward, binding the structure.
Roots from above.
Trees from below.
They intertwined—
Forming a vast, living sanctuary.
Lewis cast Daylight, fixing it permanently within the chamber.
A substitute sun.
Illuminating the growth.
An underground forest temple was born.
Finally—
He placed the Scholar's Moonstone at the center, atop a natural altar formed by intertwined branches.
This ancient druidic relic, thousands of years old, radiated symbolic power.
It became the sanctuary's core.
The moment it settled—
A sacred force descended.
Even the portraits in the Map Chamber felt it.
Not divine.
But—
Nature itself.
Druids did not draw power from gods.
They drew from the world.
And in moments like this—
Nature could rival a deity.
Within the sanctuary—
The corrupted energy was suppressed.
Gradually—
It began to purify.
Hope replaced malice.
Life replaced decay.
Lewis estimated—
Two to three years.
That was all it would take.
Then—
The energy would become pure.
Usable.
A perfect foundation.
For creating an Heroic Spirit.
That was his true goal.
Because in its original state—
This power was poison.
Corruption.
If used as-is—
The result wouldn't be Ravenclaw.
It would be an Alter.
A being drowned in all the world's evil.
Even gods couldn't withstand that.
So no—
He hadn't been lying to the portraits.
Yes, he had his own motives.
But he was also removing a catastrophic threat.
And in that sense—
Hogwarts was fortunate to have him.
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