Fate's Slave - Shadow Slave X Honkai Star Rail

Far beneath the fractured Overworld of Belobog, where the Underworld stretched into a vast cavern riddled with cracks, Aventurine hovered in place with a calm that felt almost detached from the devastation below.

The polished surface of his armor reflected the dim, glow in shifting fragments, light bending strangely through the haze that hung over the battlefield. His posture remained relaxed, but his attention was precise, his gaze moving methodically across the chaos as he tracked movements and identified anything that threatened to disrupt the fragile balance that had formed.

The two Nightmare Gates pulsed like open wounds, embedded into existence with a steady, malignant rhythm. From the collapsed opening above, where the Overworld had torn into the Underworld, a continuous stream of Nightmare Creatures poured downward. Their descent was uncontrolled, bodies crashing into the ground with brutal force before rising again to join the ongoing conflict. There was no formation, no coordination, only a constant flood of violence feeding into an already unstable battlefield.

Monsters fell first, their forms twisted and incomplete, followed by Demons with twisted intelligence. Occasionally, Devils emerged, and their presence alone shifted the atmosphere, pressing down on everything nearby with an unnatural weight as they unleashed their Abilities. Mixed among them were the draconic entities born of True Darkness, their immense bodies armored in obsidian scales that absorbed light rather than reflecting it.

When these creatures struck the ground, the impact alone reshaped the terrain. Shockwaves rippled outward, crushing anything caught beneath them, while from their hollow eye sockets poured an endless stream of True Darkness. It spread rapidly, swallowing the battlefield in a suffocating tide that consumed both ally and enemy alike.

Opposing them were the wolves, creatures that seemed less like living beings and more like walking infestations. Their bodies were uneven, covered in fungal growths that pulsed faintly as spores drifted outward in a constant haze. The effect of those spores was subtle at first, but devastating in practice. Any creature that entered that cloud began to falter, not from physical damage, but from a breakdown in thought.

It was not simple confusion.

It was overload, a collision of instinct and cognition that left the affected creature unable to act with clarity. Movements became erratic, reactions delayed or misaligned, until the creature eventually devolved into a frenzy where survival no longer mattered.

The battlefield stabilized into a brutal equilibrium. Dragons tore through wolves with overwhelming strength, while the wolves eroded their enemies from within, dismantling their minds rather than their bodies. Neither side could fully dominate the other, and so they remained locked in a cycle of mutual destruction that served, at least for now, as a containment of greater danger.

Aventurine observed this balance with quiet interest, though his attention sharpened as the flow from above shifted. The rhythm of falling creatures broke, replaced by something heavier, something that seemed to warp the air before it even appeared.

When it arrived, the impact was catastrophic.

A massive dragon descended from the Overworld’s Nightmare Gate, its body far larger than anything that had come before. It struck the ground with overwhelming force, sending a violent tremor through the entire Underworld. The shockwave flattened the surrounding area, crushing countless creatures beneath its sheer mass as the fractured terrain split even further.

Its form was immense, defined by four colossal wings folded tightly against its body. Obsidian scales layered across it like armor, and its hollow eye sockets leaked an overwhelming flood of True Darkness that spread outward almost instantly.

Aventurine exhaled slowly as he took it in, his expression shifting only slightly.

The dragon rose, and with it, the darkness expanded. The battlefield was swallowed in a growing tide of black, creatures disappearing beneath it as they struggled briefly before being consumed. Despite that, the wolves did not retreat. They surged forward, their howls cutting through the cavern as their spores thickened into a near-visible fog.

The clash between the two forces escalated immediately. True Darkness collided with the mind-altering haze, tearing through everything caught between them. For a brief moment, it seemed as though the dragon would overwhelm them entirely, its raw power eclipsing anything the wolves could offer.

Then the second Tyrant emerged.

From the depths of the Underworld’s Nightmare Gate, a massive figure forced its way into existence. Its body resembled that of the wolves, but magnified to a grotesque scale, its limbs elongated and twisted while fungal growths pulsed violently across its flesh. The moment it roared, the air itself seemed to distort.

The spores intensified.

They spread outward in a concentrated wave that struck the dragon directly. For the first time, the massive creature faltered, its movements stuttering as its mind fractured under the sudden assault. Its behavior shifted, becoming erratic as instinct overwhelmed reason, but its power did not diminish.

True Darkness reacted violently.

Constructs formed instantly, jagged and relentless, erupting outward from the dragon as extensions of its will. They slammed into the Tyrant repeatedly, carving through its body with brutal efficiency. The battlefield around them collapsed further as the two forces clashed, each exchange tearing apart the ground beneath them.

The Tyrant pushed back, its spores continuing to corrode the dragon’s mind, but the imbalance became clear. The constructs overwhelmed it, piercing through its defenses again and again until its movements slowed and its form began to fail.

Eventually, it collapsed.

For a brief moment, the battlefield stilled.

Then a new figure emerged.

From the Nightmare Gate, a humanoid shape stepped forward. It was small compared to the monsters around it, but its presence carried a weight that immediately drew attention. It moved without hesitation, its form blurring as it crossed the battlefield in an instant.

A flash of motion.

The dagger in its hand cut once.

The Tyrant’s head separated cleanly from its body.

Aventurine’s gaze narrowed slightly as he recognized it for what it was.

’Skipping everything else and going straight for Great Devils, huh?’

The Gate Guardian had arrived, and while its presence was dangerous, it was also predictable in its role. That predictability, at least, made it manageable.

Above, the Overworld’s Nightmare Gate surged again. A dense flood of True Darkness poured from it, far more concentrated than before, and within that darkness, another massive shape began to emerge.

Below, something responded.

A humanoid wolf-like Devil stepped forward, its form more refined than the others yet no less monstrous. Its horns twisted upward like roots, and in its hand it held a dagger shaped from a fang. Its gaze locked onto the emerging dragon with focused intensity, completely unaffected by the chaos surrounding it.

It moved without warning.

The ground shattered beneath it as it launched upward with explosive force. In an instant, it reached the Gate, grabbing the dragon’s head as it forced its way through. With a violent motion, it tore the creature free and drove its dagger forward.

The dragon reacted immediately, its claw intercepting the strike as its wings spread wide. With a powerful beat, it took flight, carrying both of them upward as they continued their clash midair. The Wolf Devil clung to it, refusing to release its hold as they ascended into the space above.

Aventurine clicked his tongue softly as he watched them disappear.

The two Great Devils had left the battlefield, taking the most immediate threats with them. What remained below was still dangerous, but far more manageable in comparison. Furthermore, his instinct told him that they were both Gate Guardians, so the Nightmare Gates wouldn’t bring out anything else for a very long time. Certainly not right now, at least.

His attention shifted back to the war beneath him.

Without the Tyrants, the remaining creatures would eventually destroy each other. That outcome aligned perfectly with what he needed, as it reduced the number of threats he would have to deal with directly. With the humans already evacuated by Clara’s automatons, there was no longer any need to divide his attention.

He raised a hand, summoning a Memory.

A white roulette ball appeared in his palm, smooth and unassuming. He flicked it upward, and behind him, a massive roulette wheel materialized, spinning rapidly as the ball bounced across its surface.

"Red."

It rolled for a moment before settling.

Aventurine’s lips curved slightly.

"Lucky me~"

The result favored him.

Power surged through his body, the enchantment taking hold instantly as his armor gleamed brighter in response. The faint hum of energy around him intensified, reinforcing his already formidable presence.

Satisfied, he descended.

The moment he entered the battlefield, the surrounding Nightmare Creatures reacted immediately. Their attention snapped toward him, drawn to the presence of a human soul that stood out sharply amidst the corruption.

They lunged.

He met them without hesitation.

His movements were precise and controlled, each strike deliberate as he tore through them one after another. There was no wasted motion, no unnecessary effort, only efficiency as he dismantled anything that approached him. 𝙛𝓻𝒆𝓮𝒘𝙚𝙗𝒏𝙤𝙫𝓮𝒍.𝓬𝒐𝙢

***

In the Robot Settlement, a massive steampunk railgun rotated into position. Its mechanisms groaned as it aligned with its target before firing a shot powerful enough to tear through the ceiling of the Underworld.

The impact shattered the structure completely.

A portion of the Overworld collapsed downward, debris raining into the Underworld in massive chunks of stone and ice. Automatons responded instantly, firing beams of energy upward to intercept and destroy the falling debris before it could reach the ground.

High above, the Drake Devil and Wolf Devil were caught in the aftermath.

A precise shot struck the dragon’s wings.

It did not destroy them, but it disrupted their balance enough to destabilize their flight. The two Great Devils spiraled downward, their clash continuing as they descended uncontrollably.

When they hit the ground, the impact was devastating.

A mountain collapsed instantly, the force of their landing sending ripples through the earth as the terrain fractured and shifted like a liquid surface under pressure.

And in the midst of that destruction, Sunny and Cocolia continued to fight.

The chaos around them did not slow them, nor did it divert their focus. Sunny’s chains lashed outward, wrapping around Cocolia as he swung her into a falling mass of stone. The impact shattered it instantly, debris scattering in every direction.

He shifted immediately, his body dissolving into shadow as the rain of debris passed him harmlessly. When he reappeared, he was above her, his chains already moving as they snapped around her neck.

They tightened without hesitation.

"You’ll never breathe again!"

The force behind them dragged her upward as the battlefield collapsed around them, his intent absolute as he locked her in place and continued the fight without pause.