Boom!
The lake surface exploded!
The Monster Rex, Amphisbaena, burst out like a breaching whale, azure flames already gathered within its jaws.
It sprayed the inferno toward the girls, who had not yet managed to fully regroup, clearly intending to stop them from gathering together again.
'That's is the Tyrant of the Labyrinth for you. It has a bit of intelligence, but it really is single-celled,' Rayleigh thought.
Rayleigh instantly appeared directly above Amphisbaena's head.
Before he could act, the crimson dragon head had already reacted, immediately roaring at him.
But Rayleigh had already prepared for that counterattack.
He covered his entire body in Reiryoku, forming a dense barrier to resist the kinetic impact.
Seeing that the roar proved useless, the crimson dragon head decisively opened its mouth, bared its massive fangs, and bit at him.
"Uchinekko!"
"Red!"
"Strengthened Thread!"
At the perfect moment, Ryuu, Kaguya, and Lyra stepped in and attacked together, effectively restraining the crimson dragon head.
Below them, the Familia's vanguard tank, Asta, launched a heavy shield bash directly at Amphisbaena's abdomen.
Although the powerful collision did not cause obvious physical damage, it still hindered Amphisbaena's momentum for a crucial instant.
Rayleigh seized that fleeting chance and, in that exact same instant, mobilized his Reiryoku.
He had already more or less mastered Blut Vene before, so this time he attempted the exact opposite technique—Blut Arterie.
This time, instead of fortifying his entire body defensively, he concentrated the raw power entirely into one single part for offense.
That was precisely why Blut Vene and Blut Arterie could not be utilized simultaneously.
Blut Vene was a Quincy technique that exponentially raised the body's defensive power.
Conversely, what Blut Arterie strengthened was absolute attack power!
"Hah!"
Rayleigh's descending strike directly stabbed his Zanpakutō straight into Amphisbaena's head.
The steel pierced the thick dragon scales, shattered through the bone skull, and drove the entire length of Hyōrinmaru deep into the azure dragon head.
Then came the next critical step—
He poured his remaining Reiatsu directly into the blade, letting the volatile radiance gathered at the sword's tip violently erupt.
"Getsuga Tenshō."
Rayleigh's face remained entirely cold as he spoke the release.
A massive crescent slash exploded from inside the dragon's head.
The terrifying destructive power was so immense that raw Reiatsu burst outward from within its very brain.
Bang!
One of Amphisbaena's heads exploded entirely on the spot!
Only the severed, long neck remained, twitching wildly in the air.
At that exact moment, Rayleigh felt a sudden wave of emptiness, and the Bankai constructs behind him became faintly transparent.
Less than two seconds after his boots landed on the ice, his Bankai automatically deactivated because he could no longer maintain the spiritual output.
As his Reiatsu sharply declined, Rayleigh staggered forward and barely managed to steady himself on his feet.
'Was the Reiryoku consumption simply too much...'
Although this boss battle had not seemed especially dangerous on the surface, that illusion existed only because he had not relaxed his focus from beginning to end, fighting at his maximum power the entire time.
Especially the sheer volume of Reiryoku consumed in rapidly reshaping the entire aquatic terrain was practically enormous.
On top of that heavy drain, he had utilized high-level Kidō above number sixty multiple times in rapid succession.
Besides all that, Hyōrinmaru's innate Reiatsu consumption was also extremely severe—its truly worthy of the title of the strongest ice-and-snow type Zanpakutō in existence!
That kind of active drain was almost three times that of Sakanade, five times that of Ruri'iro Kujaku—and roughly ten times that of Haineko!
If his Magic-related attribute had not successfully broken through the SS-Rank threshold, he might not have even been able to physically bear the burden of the release.
Even so, he could intuitively tell that at most, he had only brought out a meager few percent of Hyōrinmaru's true power.
Even a peerless prodigy like Tōshirō Hitsugaya had spent an entire century without truly mastering Hyōrinmaru's completed state.
According to Kyōraku Shunsui, another hundred years later, Hitsugaya possessed the potential to surpass even him in overall strength.
From that simple evaluation alone, one could clearly see both Hitsugaya's monstrous talent and Hyōrinmaru's devastating power.
Two hundred years of concentrated growth was worth a thousand years of grueling training for other Shinigami.
And those "others" were already considered the one-in-a-thousand, or even rarer, kinds of elite geniuses within the Seireitei.
At last, one of the heads had been permanently dealt with—and it was the azure dragon head primarily responsible for the magical offense.
The remaining crimson dragon head simply no longer posed a fatal, wiping threat to the vanguard.
That was not only Rayleigh's judgment, the battle-hardened girls of the Astraea Familia thought exactly the same.
But the Monster Rex, Amphisbaena, was not going to wait quietly for its inevitable death.
It suddenly raised a massive claw and viciously smashed it down toward the "insects" scurrying beneath it.
When Asta saw that the beast's target was Noin, she hurried forward and raised her steel shield to protect her vulnerable companion.
Bang!
A howling, violent wind rang past her dwarven ears.
When she finally came back to her senses, Asta found herself flying backward through the air at a terrifyingly high speed.
She had been effortlessly swatted away.
Amphisbaena was a true Floor Boss—the undisputed Tyrant of the Labyrinth.
Its raw ability values surpassed those of ninety-nine percent of Adventurers at the exact same level, roughly equal to the full-force physical attack of a peak Level 5 Adventurer.
Asta was sent flying immediately upon impact.
Noin was caught in the kinetic aftermath, but she was only blown back a few meters by the resulting wind pressure.
The dwarf girl genuinely panicked.
She felt numb and incredibly weak all over, entirely unable to gather her physical strength to adjust her landing.
Crack!
A huge, jagged fissure split open across the heavy shield in her hand, and it violently broke apart mid-flight.
"Asta!" Rayleigh tensed up in alarm.
He quickly brought two fingers together and made a sharp, slashing motion.
A resilient hammock made of Reiryoku appeared directly in the trajectory the girl was flying.
The dwarf girl landed squarely on the hammock and felt as though she had crashed onto something extremely soft, yet also highly resilient.
'Bakudō #37: Tsuriboshi!'
'Now I really have no Reiryoku left at all. I can't even use Kaidō anymore.'
"The finishing blow!"
Alise swung her burning sword and, with all her remaining physical strength, completely cut off the crimson dragon head.
With both of its heads fully severed, the outcome of the boss battle had already been definitively decided.
Just as Neze from the vanguard group was about to cheer in victory, a sudden, volatile change occurred on the side of the severed azure dragon head.
The thermal flames Amphisbaena had gathered internally earlier had completely gone out of control and suddenly erupted, instantly causing a violent spontaneous combustion.
Its massive, headless body was set entirely ablaze by the chaotic azure flames.
The girls immediately backed away on their own survival instincts.
Those were Amphisbaena's signature azure flames—even being brushed by a tiny ember of them could cause an Adventurer to ignite on the spot.
Splash!
Amphisbaena's enormous burning body fell heavily into the deep lake.
The lake surface immediately let out loud, violent hissing sounds.
That steam was caused by the intensely burning flames chemically reacting against the freezing lake water.
"We did it?"
"We did it!"
"We defeated the Tyrant of the Labyrinth! We actually beat that two-headed dragon!"
"Uh, does this mean the expedition is finally over?"
The girls looked at each other in disbelief.
Only after a long, quiet moment did they finally realize what had truly happened. They hugged each other tightly and cheered loudly in celebration.
Subjugating a Monster Rex—that was something truly worth boasting about to the Guild, and also a honor for their Familia!
"Are you alright?"
Kaguya came to Rayleigh's side, grabbed one of his arms, and directly hoisted his exhausted body up.
The faint, pleasant fragrance from the girl's body drifted into his nose.
It made Rayleigh's tired spirit stir slightly.
"Yeah, I'm fine. I just completely used up all my magic power."
With his body leaning against the girl's soft form, Rayleigh suddenly no longer felt the sharp pain of his completely emptied Reiryoku.
Instead, he even found the close proximity a little enjoyable.
Seeing his relaxed reaction, Kaguya smiled faintly.
But very soon, her expression dimmed again, and a trace of memory appeared in her eyes.
She, who had personally executed the man she loved, still had not managed to walk out of the shadow of that traumatic past.
The true face of the girl whose hands were forever stained with the blood of her first love was not that of a pitiful, lovely maiden—but of a cold and merciless… Asura.