The Book of Destiny - The Last Oracle, #9

Helena has come far from the day she became custodian of Abernathy's, the world's only living oracle. Now, she faces her greatest challenge yet: the oracle's prediction that it, and she, will end. As monstrous invaders strike city after city, leaving death and destruction behind, the Wardens scramble to defend humanity. Weakened by infighting, they turn to Abernathy's for guidance and strength. But the oracle's cryptic guidance may no longer be enough. With time running out, and her allies falling one after another, Helena faces the terrifying possibility that saving the world will mean her death.