The Nocturn were a race of vicious and merciless predators known throughout Mutter's Spiral. They were masters of disguise, able to grow an outer shell which precisely mimicked the life form they hunted. This pliable shell was an evolution of their vestigial wings, and like a ladybird's, opened and closed. They were susceptible to bright lights and so preferred to reveal themselves at night.
They were behind the Game of Death, a lure for humans. These humans were hunted and consumed, with the chance to win by surviving the night of a "murder mystery" hosted at Devastation Hall in the Silver Devastation. (PROSE: The Game of Death)