Complex sentence: This Hawkman was Carter Hall, a reincarnation of an ancient Egyptian prince, Khufu, who had in the modern day discovered that the mysterious "ninth metal" could negate the effects of gravity and allow him to fly.
Split into simpler sentences: This Hawkman was Carter Hall, a reincarnation of the ancient Egyptian prince, Khufu. Hall discovered that the mysterious "ninth metal" could negate the effects of gravity and allow him to fly.