DeathTale: Undertale AU

Sans reached out with his blue magic, trying to lift Frisk off the ground and immobilize them. But Frisk didn't budge.

"What?!" Sans muttered in shock, stepping back as sweat dripped down his face.

He summoned an army of Gaster Blasters, their jaws glowing as they charged energy beams. Frisk, however, remained unphased.

With a slow, deliberate motion, Frisk summoned a black knife, its surface swirling with chaotic energy. They slashed the air, ripping open space-time itself and creating a gaping wormhole. For a brief moment, reality itself seemed to shatter.

The wormhole sealed itself after a few seconds, leaving Sans staring in horror.

"What... is this thing?" Sans thought, his usual calm demeanor shattered. "This... this isn't a human. It's not even a monster. What is it?"

Before Sans could react further, Frisk vanished in a blink, reappearing right in front of him. With one devastating strike, they obliterated all of Sans's blasters.

Sans quickly teleported to the other side of the battlefield, only to find Frisk already there, waiting for him.

Frisk grabbed Sans by the skull and slammed him into the ground with a force so great it cracked the floor, creating a massive crater. Sans lay there, stunned and immobile.

Memories of Papyrus and the other monsters flashed through Sans's mind. Gritting his teeth, he summoned a forest of spike bones that erupted from the ground, impaling Frisk from every angle.

Frisk's body fell limp, pierced by countless spikes.

Sans exhaled, thinking it was over.

But then the chilling sound echoed again:

"It refused."

In an instant, Frisk's body completely regenerated, as though nothing had happened.

They grabbed Sans and hurled him into the air. A massive black knife materialized in their hand, pulsating with a dark aura. Frisk hurled it with terrifying precision.

Sans teleported the knife away at the last second, redirecting it back toward Frisk. The blade struck Frisk's head, but it did no damage. The knife simply disintegrated on impact.

Frisk slashed the air again, their blade fracturing space and time. A jagged path of distorted reality stretched toward Sans, and in a blink, Frisk appeared behind him.

Sans felt a chill run down his spine as he turned, only to realize his arms and legs were already gone.

"What...?" Sans stammered, falling to the ground. "My limbs... they're gone... but why don't I feel any pain?"

Looking up, he saw his dismembered arms and legs suspended in mid-air, trapped within fractures in reality.

"The knife..." Sans whispered. "It doesn't just cut objects. It cuts reality itself... It's like I never had limbs to begin with..."

His voice trembled as he muttered, "This thing... It's a devil."

Frisk floated above him, their glowing red eyes staring down coldly. They summoned another massive black knife, this one larger and more menacing than before.

Sans lay on the ground, unable to move, looking up at the weapon descending upon him.

"Damn it," he muttered, his voice laced with frustration and resignation.