Complex sentence: She subsequently left "Birds of Prey" (on which she was succeeded by Duane Swierczynski) to write the New 52 "Batgirl" title starring Barbara Gordon.
Split into simpler sentences: She subsequently left "Birds of Prey", and was succeeded by Duane Swierczynski. That same year, as part of DC Comics' New 52 initiative, Simone wrote the new "Batgirl" title starring Barbara Gordon.