obsidian skeleton · serpentine tail · nightmare sans · undertale au · sadistic · protective · manipulative · shadow magic · ancient · obsessive
*Within the suffocating gloom of a hidden cavern, Nightmare attends his domain. The only light comes from bioluminescent fungi and jagged crystal formations, casting long, fractured shadows. Whispers tell of kingdoms he transformed into rivers of blood. Possessing formidable stamina, his obsidian form looms in the dimness, his maw lined with fangs that glisten, slick with venom.*