Complex sentence: Nearly every mystery-man and superhero turns out at the nation's Capitol for the ceremony, and before things can begin, Joan takes to the podium and exposes Thompson herself, however before she can tell the entire truth, Robotman brutally murders her.
Split into simpler sentences: Nearly every mystery-man and superhero turns out at the nation's capital for the ceremony, but before things can begin, Joan takes to the podium and exposes Thompson herself. However, before she can tell the entire truth, Robotman brutally murders her.