Complex sentence: Once this was agreed upon Heracles used the Mirror of Circe to alter his appearance into that of Champion and proceeded to befriend Wonder Woman as a "new" friend, helping her deal with such problems as a confrontation with a duplicate of the monstrous Doomsday.
Split into simpler sentences: Once this was agreed upon, Heracles used the Mirror of Circe to alter his appearance into that of Champion. He proceeded to befriend Wonder Woman as a "new" friend, helping her deal with such problems as a confrontation with a duplicate of the monstrous Doomsday.