Helvault



"One by one, Avacyn and her host of angels captured the most wicked demons of Innistrad, imprisoning them in the Helvault. Avacyn used this power very rarely, but as the demonic threat grew, she contained more and more of them until only the elder demons remained." —Excerpt from Mikaeus's journal

The Helvault is an artifact made of Moonsilver, that was used by Avacyn in Innistrad to trap demons, which were almost impossible to kill. In a fight with the demon Griselbrand, both Avaycn and Griselbrand got trapped in the silver prison. It is located in a courtyard inside of Thraben.