Shaffar's Stasis Chamber Key

Shaffar's Stasis Chamber Key is used to open the Stasis Chamber of Nexus-Prince Shaffar, and summon the felhound Yor in the Mana-Tombs of Auchindoun. Yor can only be summoned if the instance is being run on Heroic Mode. The key is consumed when used.

Source
A reward from the quest Nexus-Prince Shaffar's Personal Chamber. You must be with The Consortium to receive this quest.