Firefly Music Festival have announce the lineups of the year, including Imagine Dragons, Weezer, Twenty One Pilots, Foo Fighters, Third Eye Blind, Outkast, Childish Gambino, Young The Giant, Local Natives, Tegan And Sara, City And Colour, Jack Johnson, Sleigh Bells and more. The four-day music festival will take place June 19-22 at The Woodlands in Dover, DE.