Dark Nights: Death Metal: Robin King

With a utility belt filled to the brim with weapons designed to kill every hero in the DCU, Robin King is the most sadistic soldier in the Darkest Knight evil army! Can anyone stop him from laying waste to Earth's last line of defense? And how did he become one of the Batman Who Laugh's groblins in the first place? And in the backup story, can the Robins liberate Gotham City from the Darkest Knight's control?