Ardi was already moving.
One of Nejibana's side blades hooked behind the monster's leg and dragged it off balance, while Lyra anchored Arachne's silk to the stone on both sides of the cavern and crossed the threads behind its shoulders.
The source raised its sword to cut them.
That movement exposed exactly the section of chest they needed.
Lyra pulled backward as Ardi dragged in the opposite direction, leaving the creature unable to cover its center for a brief moment.
Tsubaki was already there.
Instead of firing from a distance, she drove Tobiume's point directly against the cracked armor.
"Move after this!"
The fireball detonated at contact range.
The explosion ripped through the damaged chest, blasting grey armor and compressed magic-stone fragments outward.
The creature's upper body folded around the impact, and one arm tore free of Arachne's silk to swing blindly through the smoke.
Ais had already gone beneath it.
Gonryōmaru entered the cavity Tsubaki had opened.
The surrounding fragments began closing around the blade almost immediately, but Ais released a short pulse of electricity before they could trap it.
The packed stones lit from within, several of them shattering under the current, and for the first time the true magic stone became visible beneath the protective layer.
The moment its core was exposed, the creature stopped fighting with any recognizable discipline.
All of the careful borrowed technique vanished.
It no longer bothered with Raul's defensive control, Anakitty's counters, Ais's footwork, or Tsubaki's swordsmanship.
It simply grabbed for the person closest to the opening.
Ais.
One hand closed around her shoulder and yanked her toward the exposed chest while the other swept toward her neck.
Rayleigh was too far away to interfere without risking hitting her.
Tsubaki had not yet recovered from the close-range blast, and Ardi still had Nejibana hooked around the monster's leg.
Lyra moved first.
Arachne's silk wrapped around the creature's wrist, and this time she planted both feet and held on despite knowing how much stronger it was.
The first pull dragged her across the floor.
She refused to let go.
The creature's hand stopped just short of Ais's throat.
"Finish it! I'm not holding this thing forever!"
Ardi released the leg and swung Nejibana's shaft across the creature's waist, forcing its body sideways enough to weaken its grip on Ais.
Tsubaki recovered at the same moment and struck the sword arm with Tobiume, breaking armor and bone together until the stolen weapon fell from its hand.
Ais tore Gonryōmaru free and thrust for the exposed magic stone.
The source twisted away before the blade could reach it.
It moved faster than any of them expected, abandoning the ruined arm and using the change in Ardi's pressure to escape sideways.
By the time Ais turned, the creature had already opened enough distance to keep its exposed core away from her.
Rayleigh intercepted before it could retreat any farther.
Benihime struck the stolen sword, stopping the creature near the center of the ruined chamber.
For several exchanges, the others stayed out of the way.
By now, the stolen techniques no longer appeared as separate movements.
Raul's defensive control flowed into one of Anakitty's short counters, which carried naturally into Ais's footwork before ending with the kind of heavy strike Tsubaki used to break through a guard.
The creature had finally learned how to connect them.
Rayleigh could still see what it lacked.
Every movement had come from someone else.
Raul fought defensively because people depended on him to hold the line, and the choices behind his guard came from that responsibility.
Anakitty adjusted constantly to the people fighting beside her rather than following a collection of isolated patterns.
Ais had changed the way she fought during this expedition because her growing relationship with Gonryōmaru had taught her the difference between producing lightning and controlling it.
Tsubaki's rough, heavy swordsmanship worked because it had grown around her own strength, instincts, and years of experience as both a smith and an adventurer.
The source possessed the movements those experiences had produced, but none of the experiences themselves.
Rayleigh began feeding it situations it had never seen.
He changed distance halfway through a clash instead of finishing the exchange, forcing the creature to abandon Raul's counter and shift into Ais's footwork.
Before the transition settled, Rayleigh drove his shoulder into its chest.
The monster tried to answer with one of Tsubaki's heavier movements, but he was already inside the swing before it could gather the power that technique required.
Benihime locked against the stolen sword near the guard.
The source immediately tried to turn the bind into another copied counter.
Rayleigh held it there.
He had no intention of beating it alone.
"Now."
Tsubaki struck the stolen blade from the side.
The creature could have resisted Rayleigh or Tsubaki individually, but the two forces came from different directions.
Its grip broke before it could adjust, and the sword spun across the cavern before striking the wall.
Ardi came next, driving Nejibana behind one knee and forcing the monster down. Lyra's threads caught both arms and pulled them wide.
The creature tried to rise.
Asfi, now standing on the ground with the damaged Talaria sandal removed, threw her last small explosive behind its shoulders.
The charge detonated.
Rather than trying to damage the source directly, the blast drove it forward into the opening the others had deliberately created.
Ais was waiting.
Gonryōmaru pointed straight toward the exposed chest.
The creature saw the blade and tried to twist away, but Tsubaki caught the back of its neck with one hand and forced it into place.
"You've been copying us long enough. Hold still and watch the original."
Ais drove Gonryōmaru through the opening.
The point struck the central magic stone.
The creature's entire body tightened as every remaining fragment beneath its armor lit at once.
The damaged chest tried to close around Gonryōmaru, but Tobiume, Nejibana, Arachne, and Asfi's explosives had already destroyed too much of the structure holding those fragments together.
Ais pushed deeper.
The stone cracked.
A faint current travelled along Gonryōmaru, but she did not waste power on a larger discharge. T
he core had already been exposed, and a direct thrust would finish what the others had opened for her.
The Enhanced Species stared at her.
Throughout the expedition, its kind had watched the adventurers because it wanted to learn from them.
Ais met its gaze.
"You learned enough."
She drove Gonryōmaru through the rest of the stone.
The core shattered.
Every black line beneath the creature's armor went dark.
Tsubaki released its neck and stepped away while Lyra dismissed the threads around its arms.
Ais pulled Gonryōmaru from the wound, and the source remained upright for several seconds before cracks began spreading outward from its chest.
Its body started dissolving around the broken core.
Compressed magic-stone fragments dropped from the collapsing flesh, but without the true stone holding the creature together, none retained the glow they had carried during the fight.
The stolen sword broke apart beside the remains, leaving only scattered metal, dull crystal fragments, and ash across the floor.
Nobody lowered their guard immediately.
Rayleigh kept Benihime drawn and listened for another signal through the Dungeon walls.
Nothing answered.
The pressure that had tugged at every Zanpakutō since they entered the lower tunnels had vanished as well.
Gonryōmaru settled quietly in Ais's hand, Tobiume stopped vibrating, and the faint strain that had followed Arachne and Nejibana throughout the nest disappeared.
Asfi was the first to look away from the remains.
"The roots aren't moving."
Everyone followed her gaze.
Without the source, the black growth covering the cavern walls had already begun to dry.
Veins that had once pulsed like living tissue were turning brittle while fresh Dungeon stone pushed through from beneath them, breaking the dead growth apart and reclaiming the damaged walls.
A thick section of root detached from the ceiling and struck the floor nearby.
Nothing reacted.
Lyra finally allowed Arachne to return to its sealed form.
"So this time, when we say it's dead, we actually mean dead?"
Rayleigh gave the cavern another slow inspection before sheathing Benihime.
"Yes. The signal network is gone, the brood stopped developing when we cut the roots, and the source just lost its core. Unless the Dungeon decides to invent another problem before we reach the stairs, we're done here."
Tsubaki resealed Tobiume and rested the sword against her shoulder, looking considerably happier now that nothing remained to imitate it.
"Good. I've had enough of monsters stealing Little Ume's tricks for one expedition."
Asfi crouched beside what remained of the source and inspected the debris.
Most of the magic-stone fragments had already lost whatever unusual properties the network had given them, but a few pieces of black tissue remained intact enough to justify taking back for examination.
She sealed two samples in separate containers and stood.
"This should be enough. There's no reason to waste time collecting ordinary fragments, especially while the Dungeon is repairing the chamber."
Rayleigh looked at the walls and had to agree.
Pale stone had already covered several places where black roots had been visible only minutes earlier, and the process was accelerating now that nothing resisted it.
Staying long enough to let the Dungeon close the room around them would be an embarrassing way to finish a successful rescue.
"Then we leave. Finn's group should still be somewhere above the thirty-seventh floor, and Raul's people need proper healers before anyone worries about giving a full report."
Ardi resealed Nejibana and joined Lyra near the passage they had entered through. Both women were exhausted, although neither had suffered anything worse than minor cuts and bruises in the final battle.
Tsubaki walked over to Asfi and glanced down at the damaged Talaria sandal.
"Can you still use those?"
"One is damaged, so not properly. I can repair it once we're back on the surface."
"You want a lift?"
Asfi looked at her.
"No."
Tsubaki shrugged and kept walking. The refusal was exactly what she had expected.
Ais remained near the place where the source had died, looking down at Gonryōmaru while the others prepared to leave.
Rayleigh waited until the Zanpakutō had completely settled before walking over.
"You all right?"
Ais nodded, though her attention remained on the sword in her hand.
"Gonryōmaru is quiet."
Rayleigh knew enough about Zanpakutō to understand that silence could mean several very different things.
"Good quiet?"
Ais rested her fingers lightly against the guard and waited.
A faint spark touched her hand, far too small to be an attack and too deliberate to be accidental.
Her expression softened.
"Yes."
Rayleigh smiled and left it at that.
Gonryōmaru had once been damaged because Ais tried to force herself into power she was not ready to carry.
Throughout this expedition, she had done almost the opposite.
When the monsters began draining her releases, she shortened them.
When they copied her swordsmanship, she changed the way she fought.
When they stole Gonryōmaru's lightning, she learned to take control of the electricity rather than trying to overwhelm them with more power.
More importantly, she had begun trusting the Zanpakutō as something more than another weapon to point at whatever stood in her way.
She had made progress, and there was no reason to turn that progress into another attempt at Bankai before she was ready.
Ais resealed Gonryōmaru and joined the others.
Behind them, fresh Dungeon stone continued swallowing the remains of the nest.
The brood sacs had collapsed into dry husks, the severed roots were crumbling into dark fragments, and the wall that had once held the central mass was already close to being restored.
By the time Rayleigh reached the passage, only a single thin strand remained exposed near the floor.
The new stone growing beneath it pressed upward until the brittle tissue cracked and broke apart.
Nothing replaced it.
Rayleigh turned toward the tunnel.
"Let's get everyone home."
The six adventurers left the chamber together and began the long climb back toward the rescue party.