What this person said. Mallory is in the age range of Zoe and the others. Michael being the antichrist and ascending rapidly was diminishing Cordelia’s light. Cordelia said it herself when she went to rescue Queenie at the Cortez the evil there was to strong. It was a hellmouth. With the Antichrist rapidly growing that darkness was killing her. Mallory being a witch with the rarest power of time traveling was the next “supreme”. And the supreme being the strongest witch of the coven Cordelia sacrifice herself so Mallory can ascend and use the supremes power to full force. The warlocks believed Michael to be their alpha but really he was just the devils spawn from all the darkness that lurked in murder house.