Discovering the vaults unlocks the quest. To activate this sub-quest you’ll need to have reached Bloodmoon Island in Act 2 and have found the 3 vaults that relate to The Forgotten and the Damned side quest. How to Start the Delusions of Grandeur Quest If you're having trouble, though, this guide should help you along with a step-by-step breakdown of this quest so you can continue your progress through one of the decade's best RPGs. So in order to complete that side quest, you must get through Delusions of Grandeur. It's a sub-quest within the side quest called The Forgotten and the Damned.