Complex sentence: As he weakens, Luthor taunts him by revealing that the first missile is a decoy, headed east towards Hackensack, New Jersey, knowing that even Superman can't stop both impacts.
Split into simpler sentences: As he weakens, Luthor taunts him by revealing that the first missile is a decoy, headed east towards Hackensack, New Jersey. Luthor knows that even Superman can't stop both impacts.