Ferumbras' Ascension Quest/Spoiler

Required Equipment

 * 30 Demonic Essences

Method
Go to Darashia and find the scholar Mazurius in the northeastern part of town. When he asks you to help him stop Ferumbras from gaining godlike power, accept the quest.

Opening the gates of hell
Mazurius wants you to bring him 30 Demonic Essences. Simply give them to him.