Complex sentence: Summers eventually led a mutiny against his captors and for years the Starjammers tried to take their revenge on the Shi'ar, who were fighting a losing war of their own against the Brood.
Split into simpler sentences: Summers eventually led a mutiny against his captors and formed the Starjammers. For years the Starjammers tried to take their revenge on the Shi'ar, who were fighting a losing war of their own against the Brood.