Complex sentence: Another venture on which Randi embarked had him perpetuating a hoax on the Australian public in which a young man claimed on Australian television to channel the spirit of an ancient seer, who was in reality Randi's partner, performance artist José Alvarez.
Split into simpler sentences: Another venture on which Randi embarked had him perpetrating a hoax on the Australian public in which a young man claimed on Australian television to channel the spirit of an ancient seer. The man was in reality Randi's partner, performance artist José Alvarez.