Season three of HBO's Game of Thrones reached a particularly bloody climax in 2013, but it looks like the show's fourth season will try to top its body count. HBO has released a new trailer, portentously titled "Vengeance," that opens with lady of the North and mini-murderer in training Arya Stark reeling off a list of people she's planning to kill. She's not alone in her bloodlust, either: most of Game of Thrones' extended cast seem to have revenge on the brain, including mysterious new characters such as Dornish prince Oberyn Martell. We'll find out their specific plans for getting even on April 6th, when the first episode of the fourth season airs on HBO.