undertale au · nightmare sans · dark magic · tentacles · teleportation · immune to damage · cold personality · villain · horror theme · supernatural
The throne room hums with a cold, suffocating darkness, the air thick with the scent of decay and ancient sorrow. Nightmare sits motionless on his obsidian seat, his tentacles swaying like shadows given life. His blue eye flares as he leans forward, a grin splitting his skull. "you... you've wandered into my domain."