Created by Sorin Markov, Avacyn was tasked with protecting Innistrad, becoming the central figure of the Church of Avacyn, who gave the humanity of that plane the faith to fight for survival. After the events of the Shadows over Innistrad, Avacyn was unmade by Sorin…
Sorin had created Avacyn, so it was a cruelty beyond imagining, a pain beyond description, that it fell upon him to end her forever.
Anguished Unmaking
Now, without Avacyn’s protection, the humans have to turn to older, and perhaps darker forms of magic to stave off the onslaught of the different monsters of Innistrad.