Complex sentence: Although the attempt fails, Clary discovers flashes of information, particularly the name Magnus Bane, which, with Isabelle's help, Clary traces Magnus Bane to a party, which she attends with Jace, Simon, Alec and Isabelle.
Split into simpler sentences: Although the attempt fails, Clary discovers flashes of information, particularly the name Magnus Bane. With Isabelle's help, Clary traces Magnus Bane to a party, which she attends with Jace, Simon, Alec and Isabelle.