Note: You must have minimum level 50 and be in SURVIVOR mode.
Go see an NPC named Ignus that you will find immediately on the left in the small house when leaving the temple of Silversky. He will offer you either to “get” a parchment, or to “sell” it to you. Say “procure” and you will get the scroll in exchange for [10 Bone of Bravery] and [1 Potion of Heroism].
Or
Say “sell” and you will get a scroll in exchange for 300k golds.
Reward: Access to the 3rd Stoneheim Island