The Scroll of Skyriss

The Scroll of Skyriss is a quest item only lootable by players on the quest WANTED: The Scroll of Skyriss. The quest is a random daily heroic quest from Wind Trader Zhareem in Lower City.

Source
This item drops from Harbinger Skyriss in the Arcatraz on heroic mode for those on the quest WANTED: The Scroll of Skyriss.