Fate's Slave - Shadow Slave X Honkai Star Rail

In the Overworld, against the horde of Nightmare Creatures, there were three main combatants, and each of them embodied a different kind of overwhelming force that reshaped the battlefield simply through their presence.

Aventurine moved through the air clad in his glamorous armor, its polished surfaces gleaming even beneath the dim and fractured light of the war-torn sky. The enchantments woven into it allowed him to fly with unnatural ease, his figure darting through the air in sharp, controlled arcs as he descended upon his enemies with devastating precision. Every movement carried intent, and every strike of his armored fists released the full weight of his Transcendent might, crushing Nightmare Creatures into broken fragments before they could even react. There was no wasted motion in his actions, no unnecessary flourish, only an efficient and almost casual brutality that stood in stark contrast to the chaos surrounding him.

Below him, Serpent had already begun to shift.

Moments ago, it had taken the form of the Architect of Lost Preservation, a figure that carried an eerie, composed authority even in the midst of battle. That form did not last. Shadows gathered around it in a dense, suffocating mass before collapsing inward, reshaping its body into something far more sinister. The transformation was not gradual, nor was it subtle. It was immediate, as if the very concept of its existence had been rewritten in an instant.

What emerged was the shadow of a Fallen Devil.

The creature stood more than two meters tall, its entire body encased in gothic armor forged from a dull, lusterless anthracite steel that seemed to swallow light rather than reflect it. Every inch of that armor was covered in intricate engravings, patterns so detailed and so deeply etched that they appeared almost alive. The images they formed were not meant to be understood, only endured, and even a fleeting glance at them carried the unsettling sense that prolonged observation would lead to madness.

The helmet that crowned its form was adorned with curved horns, remnants of something that might once have been wings, now twisted into a shape that emphasized its unnatural silhouette. Within the narrow fissure of the visor, two ghastly red flames burned steadily, their glow neither bright nor dim, but oppressive in a way that defied simple description.

When it stepped into the True Darkness that blanketed the battlefield, everything about it changed.

The Darkness released by the Underworld Drakes, Wyverns, and Dragons — beasts that corresponded to Devil, Tyrant, and Terror Classes respectively — was not ordinary shadow. It was something deeper, something ancient, and when the Black Knight was enveloped by it, its presence became almost impossible to track. It moved faster than before, its already formidable speed amplified to the point where it blurred into obscurity. There was no sound to accompany its steps, no disturbance in the air that could betray its position, and every motion it made carried an enhanced physical force that turned it into an unstoppable engine of slaughter. Attacks that landed against its body did not linger. The damage vanished almost instantly, repaired by the surrounding darkness as if the concept of injury itself could not persist within its domain. As long as it remained within that True Darkness, it was effectively immortal.

Above them, Saint maintained her position.

From her vantage point, arrows of pure shadow fell in a relentless barrage, each one striking with unerring precision. They pierced through the Underworld abominations with enough force to stagger even the larger creatures, but their true effect was far more insidious. Whenever one of those arrows struck a creature’s shadow, the result was immediate and absolute. The target froze in place, its entire body locking up as if time itself had been halted for it alone. In that brief moment of enforced stillness, Aventurine or the Black Knight would close in, eliminating the immobilized creature without resistance.

For a time, this synergy held the battlefield together.

Then, the situation shifted.

A Corrupted Beast stepped through the Nightmare Gate.

Its arrival was abrupt, its presence immediately altering the flow of battle as its aura pressed outward with a suffocating weight. Aventurine reacted without delay, diving from the sky with explosive speed as he intercepted the creature before it could fully establish itself. His fists struck with overwhelming force, the impact reducing the Corrupted Beast to shattered remains in a matter of seconds.

It should have ended there.

It did not.

Another stepped through the Gate.

Then another.

Then another.

Within moments, what had begun as a manageable threat escalated into something far more dangerous. A dozen Corrupted Beasts emerged in rapid succession, their numbers swelling as they poured into the Overworld. Among them, larger figures began to appear, Monsters whose sheer size and presence made them impossible to ignore.

Saint responded immediately.

An arrow descended from above, carrying a distinct presence that set it apart from the others. When it struck, lightning erupted outward in branching arcs, chaining from one target to another as it tore through the Corrupted abominations. The Second Strike of Thunder unleashed its full force, its electrical fury consuming several of the creatures outright.

But most survived.

The attack, for all its power, was only an Ascended arrow.

It was not enough. 𝙛𝒓𝒆𝙚𝒘𝒆𝓫𝙣𝓸𝙫𝓮𝒍.𝒄𝒐𝓶

Aventurine felt it then.

A premonition.

The shift in probability, the subtle warning that something critical had reached its threshold. His expression did not change drastically, but his voice carried a note of certainty as he spoke.

"It’s time. You might want to move!"

The Black Knight reacted instantly.

Its form blurred as it moved toward the backlines, where IPC soldiers and Silvermane Guards maintained their positions from afar. Before any of them could register what was happening, it struck. Its movements were too fast, too precise, and within moments, every single one of them had been rendered unconscious. There was no resistance, no drawn-out struggle, only a swift and efficient removal of human presence from the battlefield.

Then, the transformation came again.

The Black Knight dissolved, its armored form collapsing into shadow before expanding outward into something far greater. Serpent’s Soul Beast form emerged in full, its immense body stretching across the battlefield as its onyx scales shimmered faintly under the moonlight. Each scale was massive, large enough to shield an entire body, and together they formed a surface that seemed both solid and fluid at the same time.

From its back, six insectoid wings unfurled.

They were vast, their structure delicate yet powerful, each membrane displaying countless shades of black that shifted subtly with every movement. When they beat, the resulting gusts of wind crashed against the earth below, sending debris and snow scattering in violent waves.

Beneath its elongated body, two massive arms hung, their scaled surfaces matching the rest of its form. Each hand ended in three elongated fingers, each tipped with a claw sharp enough to tear through steel without resistance. Its head had changed as well, its features becoming more pronounced, more predatory. The gap between its jaws revealed rows of additional teeth, each one gleaming faintly as if it had been honed to perfection.

Its eyes were not eyes in the conventional sense.

They were voids.

Deep oceans of shadow that churned and shifted, their depths swirling like a storm contained within an endless abyss.

Serpent moved with purpose.

It did not engage the Corrupted horde directly. Instead, it glided across the battlefield, its massive body moving with an almost eerie grace as it opened its maw. One by one, the comatose forms of the Awakened soldiers were gathered and swallowed, drawn into its body where they would remain unharmed, protected from the devastation unfolding around them.

Above, Aventurine pulled back, rising higher into the air as he observed the unfolding sequence.

Everything was aligning.

Then Saint moved.

She leaped down from her perch, landing with controlled force as she raised her leg, her gaze fixed on the approaching Corrupted creatures. There was no hesitation in her expression, no uncertainty in her posture. Only disdain.

Cracks of gold spread across her armor.

They appeared slowly at first, then rapidly, branching outward like fractures in glass as the energy within her reached its peak.

Then she brought her leg down.

The Overworld responded.

The surface of the earth did not simply break. It collapsed.

A massive section of the battlefield gave way, the ground crumbling and falling as if it had lost all structural integrity in an instant. Within a radius of nearly a hundred meters, everything was dragged downward, the terrain itself giving way to reveal the depths below.

The Nightmare Gate remained suspended, untouched by the Destruction.

Everything else fell.

The Corrupted abominations, the debris, the shattered remnants of the battlefield — all of it plunged into the Underworld beneath. Below, another Nightmare Gate had already opened, its presence drawing forth a different wave of creatures.

The collision was immediate.

The Underworld abominations met another kind of Underworld abominations — one being from the Dream Realm’s Underworld and the other invading Belobog’s Underworld. Draconic claws met the fangs of nightmarish wolves, and the confined space of the Underworld became a slaughterhouse as the two species of Nightmare Creatures tore into one another without restraint.

The plan had been simple.

Initiate a war between them.

And it worked.

As long as more creatures continued to emerge from the Overworld’s Nightmare Gate, they would fall directly into the Underworld, feeding the conflict below and keeping both sides occupied. It was not a perfect solution, but it was effective enough to buy time.

Of course, the danger had not vanished.

Humans were still their preferred prey, and approaching too closely would mean inviting disaster.

Aventurine did not linger.

He turned and flew away, his figure retreating from the immediate vicinity as he positioned himself for what would come next. Serpent followed, its massive form lifting into the air as it moved in the direction of Sunny, its purpose clear even without words.

Saint remained for only a moment longer.

She felt the True Darkness around her respond, the shadows rising to meet the golden cracks that spread across her armor. The two forces merged, darkness flooding into the fractures as her form began to dissolve.

A moment later, she was gone.

Vanished into the shadows as if she had never been there at all.