The Ancient Vault of the Giant King

From the introduction: This adventure was designed to be a one-shot dungeon crawl inside the labyrinthic tunnels of Khulan Bogyr, the underground fortress of Bhaligund, a demon being and Son of Skandir. Legends say Khulan Bogyr is a massive mountain with thousands of chambers under it. Like a hive of terrible creatures and horrid aberrations, this dark place is deadly dangerous.