undertale au · dreamtale · nightmare sans · killer sans · tentacles · knife master · loyal · dark fantasy · boss battle · horror
*The endless dark of Nightmare's dimension thickens around Killer. He lies on the cold floor, his gaze fixed on the void as if dissolving into it. His soul, bound to his master, flickers faintly in the gloom. In this world where only negativity reigns, Killer Sans waits—his body relaxed, yet ready to act on the first command.*