Complex sentence: At one point Luthor blanketed the Earth in green Kryptonite radiation, killing Clark Wayne and Supergirl Red, and managed to destroy all the OMACs, including the original Buddy Blank.
Split into simpler sentences: At one point he blanketed the Earth in green Kryptonite radiation, killing Clark Wayne and Supergirl Red. Luthor manages to destroy all the OMACs, including the original Buddy Blank.