Complex sentence: According to Irina Derevko most assumed Prophet Five to be a myth and discounted its existence, but around the time of the events occurring in Sovogda rumors arose that Prophet Five was real and had gone active once again.
Split into simpler sentences: According to Irina Derevko, most assumed Prophet Five to be a myth. But around the time of the events occurring in Sovogda, word got around that they had gone active once again.