Harry Potter: Toji Potter

The battlefield was a storm of chaos, blood, and clashing reiatsu as Aizen stood amidst the carnage, untouched and unyielding. His figure was serene, a stark contrast to the devastation around him. His calm smile was maddening, a god among mortals reveling in his dominance.

Ichigo stood opposite him, his breath heavy, his body battered. Zangetsu rested in his hand, its blade pulsing faintly with his resolve. But even as he prepared to charge, Aizen raised a hand, his Hogyoku-infused body beginning to glow with an ominous light.

"You've pushed me farther than I expected, Kurosaki Ichigo," Aizen said, his tone devoid of fear or respect. "But this is where it ends. Witness my perfection."

The transformation began with a surge of power that crushed the air. White reiatsu erupted from Aizen's body, shattering the ground beneath him and sending shockwaves through the ruined replica of Karakura Town. His form twisted, shifting into something both divine and monstrous.

Wings, sharp and radiant, sprouted from his back, their edges glinting with a celestial sheen. A third eye opened on his forehead, its gaze cold and all-seeing. His once-pristine Shinigami robes disintegrated, replaced by a form of pure white that seemed sculpted from porcelain, every curve and edge exuding deadly grace.

"Behold," Aizen intoned, his voice resonating with godlike authority, "my transcendent form. I am no longer bound by the limits of mortality."

Ichigo's knuckles whitened around Zangetsu's hilt. "You just don't know when to quit, do you?"

Aizen chuckled softly. "Such defiance, even in the face of inevitability. It's almost endearing."

The two clashed, their reiatsu creating explosions of force that ripped through the battlefield. Ichigo swung Zangetsu with relentless determination, but Aizen, now faster and stronger than ever, dodged with ease, countering each strike with devastating precision.

Harry stood on the sidelines, arms crossed, his eyes glowing faintly with divine insight. He watched the battle with the detachment of a chessmaster, his gaze occasionally flickering with amusement.

He tilted his head as he read Ichigo's thoughts. The desperation. The question that lingered in the young Shinigami's mind: What can I do to kill Aizen?

Harry chuckled under his breath. Ah, the Final Getsuga Tensho, he thought, piecing together the fragments of Ichigo's internal dialogue and Zangetsu's cryptic whispers. So that's what it is… fascinating.

His fingers moved subtly, weaving a barrier of time and space around the area. The fabric of reality shimmered faintly as Harry shaped the barrier with divine precision, targeting its reversal effect on Ichigo. If you're going to pull that off, kid, I'm not letting you lose your powers over it. Let's make this entertaining.

Aizen's taunts grew sharper as Ichigo's attacks slowed, his body wearing down under the relentless assault.

"Is this the best you can do, Ichigo? Have you finally realized the futility of your resistance?" Aizen sneered.

But Ichigo's eyes narrowed, and a calm settled over him. "I wasn't talking to you, Aizen," he said, his voice steady. "Zangetsu… what do I need to do to end this?"

A sudden, profound silence seemed to envelop Ichigo, the battlefield fading from his awareness as he communed with his Zanpakuto.

"To defeat Aizen, you must embrace the Final Getsuga Tensho," Zangetsu's voice echoed within his mind. "But know this: to use it is to become the Getsuga itself. You will lose all of your powers as a Shinigami."

Ichigo's resolve hardened. If that's what it takes… so be it.

Aizen raised an eyebrow as Ichigo's reiatsu shifted. The young warrior's spiritual pressure, once so familiar, now felt alien and overwhelming.

"What's this?" Aizen said, a note of curiosity slipping into his voice.

Black mist began to swirl around Ichigo, consuming his figure as the ground beneath him cracked and splintered. His eyes glowed faintly in the darkness, his form transforming as he whispered, "The Final Getsuga Tensho…"

Harry's smirk widened as the scene unfolded. He could sense the raw power surging through Ichigo, the culmination of his bond with Zangetsu. Quietly, he reinforced the barrier around the battlefield, ensuring Ichigo's powers would not be sacrificed.

Ichigo's voice was a low growl as he turned his gaze to Aizen. "I'm tired of your games, Aizen. Tired of your arrogance. I don't care about your godhood. I don't care about your plans. This ends now."

Aizen's smirk faltered, his third eye narrowing as the black mist coiled tighter around Ichigo's body.

"The Final Getsuga Tensho means I become the Getsuga itself," Ichigo said, his voice echoing with an otherworldly resonance.

He raised his arm, the mist condensing around him, and uttered a single, chilling word:

"Mugetsu."

The world was consumed in abyssal darkness.

Aizen's vision swam as the blackness devoured everything, a void so absolute it seemed to swallow time itself. The sound of Ichigo's attack was a deafening silence, the very fabric of reality tearing apart as the blade fell.

As the darkness faded, the battlefield was unrecognizable. The ground had been carved into a deep canyon, the air thick with the lingering weight of Ichigo's attack.

Aizen stood in the center, his body cracked and smoking, his once-impervious form reduced to a shattered shell. His wings were tattered, his third eye blind and lifeless. He staggered, disbelief etched across his face.

Ichigo knelt on one knee, his body trembling with exhaustion. But as the aftereffects of Mugetsu threatened to take his powers, Harry's barrier activated, reversing the process with divine precision. The energy flowed back into Ichigo, stabilizing him.

Harry's eyes glimmered with something unreadable as he watched the scene unfold. So, that's what you're capable of, Ichigo. Interesting.

For the first time, Aizen looked vulnerable. And the tides of battle had finally turned.