Complex sentence: Clark Kent, formerly Superman, could not stop a dam from bursting and destroying a town; and Kyle Rayner, formerly Green Lantern, was beaten by the supervillain Sonar, an event which drives him to obsession when his Power Ring will not spark.
Split into simpler sentences: Clark Kent, formerly Superman, could not stop a dam from bursting and destroying a town. And Kyle Rayner, formerly Green Lantern, was beaten by the supervillain Sonar, an event which drives him to obsession when his Power Ring will not spark.