Mark Brooks Brendon Small Janine Ditullio Mark Brooks Brian Posehn (additional writing) Metalocalypse: The Doomstar Requiem A Klok Opera is a one-hour rock opera special for the Adult Swim animated series Metalocalypse. It was announced on May 10, 2013, by Adult Swim was released on October 27, 2013. It features all new music from Dethklok, which was also released on an album on October 29, 2013.