As we have learned in multiple Uncharted Realms, Avacyn is a construct of Sorin's to maintain a balance between the humans and the various monsters of the plane. She was tasked to protect the humans from the vampire's overfeeding. As she was released from the Helvault, Avacyn invoked the Cursemute, a powerful spell that transformed all the willing werewolves into the wolfir, and cast out the tendrils of darkness that had all but consumed the humans with her fleet of angels. Now there is another unbalance, Avacyn herself. She, and her angels, have become too powerful, the other races on Innistrad are losing. In a paradoxical turn, Avacyn created the unbalance she was responsible of maintaining. In an effort to set everything right, the angels turn on the humans. Now we see a great battle, with the human radicals of Avacyn and her Fleet on one side, and the rest of the humans on the other, along with the various surviving werewolves and vampires. The Church of Avacyn has fallen, and the world must be rebalanced.