Having exhausted two of their perception-blocking artifacts, Xaren and Ilya locked all doors and returned all the keys to their proper places.
Then, they entered the toilets and changed into a fresh set of clothes before splitting up into separate ground-floor document rooms.
They remained there until morning.
By the time the librarians arrived to start the new day, Xaren and Ilya waited for the right moment before slipping out of the document rooms when no one was looking.
They acted as though they had just arrived for work.
No one noticed a thing.
They continued working as usual for the next few days until the next scheduled day for the barrier's magic power replenishment.
A different group of Archmages arrived this time, but despite being a new group, they followed the same routine as the last. Two remained after the library closed—and so did Xaren and Ilya.
Just like last time, they sensed the Archmages descending to the ground floor—still making no effort to conceal their magic power. Without hesitation, Xaren and Ilya followed.
This was the night. They had already packed everything from the inn into their magic pouches, fully prepared to leave the city as soon as their mission was complete.
Their perception blockers were already active, so they simply waited inside the first-floor document rooms until the Archmages made their move.
When the Archmages descended to the ground floor, Xaren and Ilya followed. Even with their artifacts in effect, they remained cautious, suppressing their presence as much as possible.
They carefully restrained their magic power and demonic energy, uncertain how effective these artifacts would be against the Level 300 Archmages.
They also avoided staring directly at the Archmages and kept a safe distance.
When the two Archmages entered the document room, Xaren and Ilya hid behind some bookshelves, watching closely.
Believing they were alone, the Archmages didn't bother closing the door. This gave Xaren and Ilya, who were positioned behind distant bookshelves, a clear view of how they accessed the secret room.
As Xaren had suspected, there was indeed an underground chamber.
What he hadn't expected, however, was the location of the keyhole.
It wasn't on the walls or ground—but on the ceiling.
One of the Archmages levitated using magic, flying up to insert the key into a concealed keyhole hidden behind the central lamp in the room.
The moment the key turned, a hidden door at the centre of the room silently unlocked and popped open like a latch.
Without hesitation, the two Archmages descended underground.
Xaren and Ilya remained hidden, waiting patiently.
Roughly five minutes later, they sensed the same surge of magic power as before—apparent confirmation that the barrier core prison had been recharged.
The moment it happened, Xaren and Ilya immediately retreated, rushing back upstairs into the Level 1 document room.
There, they waited until the Archmages re-emerged, locked up, and left the library.
Only then did they finally release the quiet sighs of relief they hadn't realized they were holding.
Without wasting any time, the two of them switched to their fourth perception-blocking artifacts and headed straight for the ground-floor document room.
They unlocked the door and entered the room, their gazes focusing on the lamp at the centre of the ceiling.
Xaren then grabbed the first duplicate key before activating his Unique Skill and reversing the gravity on himself.
His body lifted off the ground, but as his control was not yet perfect, he wobbled slightly in the air. He instinctively stretched his arms out to balance himself, stabilizing just enough to reach the lamp's base.
Shifting aside the lamp with one hand, he carefully inserted the duplicate key into the hidden keyhole and turned.
With a faint click, the mechanism unlocked, the door on the ground popping open like a latch.
"The way it blends into the ground... I wouldn't have believed it was there even if someone told me,"
Xaren muttered as he descended, and Ilya couldn't help but agree. The door was in the exact spot where Xaren had sat three days ago.
She pulled the door fully open, revealing a spiralling staircase leading downward.
From within, they could immediately sense dense magic power, and as they descended, the ambient concentration grew stronger.
By the time they reached the bottom, the magic power in the air was nearly three times as dense, forcing them to take a moment to adjust.
After adapting, they looked around and saw they were in a rather spacious underground chamber.
The room was filled with barrier nodes, each embedded into the ground, pulsing softly with magic power.
At the centre of the room stood a massive cuboid box.
The box was tall, almost closet-like, with black lining along its edges. Its translucent surface glowed a faint blue, the colour of the magic power drawn from the surroundings coursing intensely through its structure.
Stepping toward it, Xaren pulled out the replica key for the barrier core prison. He slotted it into the keyhole on the box's surface and turned it, disengaging the lock.
The door swung open automatically.
Inside, bound in chains, was an unconscious woman.
Her features were entirely human, normal in every way—except for one thing.
Her body was half-transparent.
The parts of her skin that were visible, where her clothes did not cover, were faintly see-through.
'She's a Spirit, alright.'
Xaren mused internally as he took out the barrier key and began unlocking the chains binding her wrists and ankles. The metal clinked softly as they loosened, and once they were completely undone, he reached in and lifted her out.
Turning, he passed her to Ilya, who adjusted her grip and held the unconscious spirit securely.
Meanwhile, Xaren reached into his pouch again, this time pulling out the dummy core they had been given. Carefully, he placed it into the barrier core's compartment.
Immediately, the barrier core latched onto it, absorbing energy from the dummy replacement.
Xaren observed for a moment, ensuring the process had begun properly. Then, satisfied, he closed the box and locked it before turning to Ilya.
"Time to go."
Without hesitation, they rushed back up the stairs.
Upon reaching the ground-floor document room, Xaren sealed the latch shut, then flew up again, using the second key to lock the ceiling mechanism behind the lamp.
He quickly grabbed the keys to Level 2 and rushed up the stairs, collecting keys up to Level 4 before heading into the left wing to bag his target grimoire.
Along the way, Xaren picked up two more grimoires he had noticed during working hours—one on Wind Magic for Ilya and another on Fire Magic for himself.
Unfortunately, he found no grimoires on Darkness Magic.
With his selections made, he hurried back down, carefully locking every level behind him and returning all the keys.
Now, all that remained was leaving the library building. And compared to everything else, that seemed like the easiest part of their plan.
They first headed to the toilets, their targets being the windows here.
Xaren unlatched a window and pushed it open. He first scanned the outside, and after spotting nothing, he jumped out.
Landing lightly outside, he turned back and spread his arms to receive the unconscious spirit Ilya passed him.
After confirming his grip on the spirit, Ilya slipped through the window as well.
Once both were outside, they shut the window behind them and turned toward the library's perimeter fence.
The fence was lined with magical defences, but Xaren wasn't concerned. He knew these sensors operated by detecting magic power.
And if even the Level 4 sensors had failed to detect them, these external defences wouldn't fare any better.
Without breaking stride, they cleared the fence effortlessly and vanished into the night.