The Crux of Darkness is a quest that ultimately rewards an Essence of the Oversoul, which is used to upgrade Eidolon Ally into Necrochasm. The quest is given upon obtaining a Husk of the Pit, which can drop randomly after killing a Hive enemy.
|Born of the Pit|
|"Upgrade the Husk of the Pit and transform it into Eidolon Ally."
|The Speaker Knows|
|"Take Eidolon Ally to the Speaker in the Tower."
|Secrets of the Hive|
|"Visit Eris Morn in the Tower to learn the ways of Eidolon Ally."
|Ally of the Dark|
|"Collect Hive power by traversing The Abyss and defeating Crota in the 390 Light version of "Crota's End" raid and killing Omnigul in "The Will of Crota" strike."
|Return to Eris Morn|
|"Speak to Eris Morn in the Tower."