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Cocoon is the opening story mission of Season of the Lost. The Guardian joins Saint-14 in following Osiris to the Dreaming City in order to find answers behind the former Warlock's involvement in Lakshmi-2's failed coup.
The Guardian lands in Harbinger's Seclude.
The Guardian breaks through the first line of Hive.
The Guardian defeats a wave of Hive and breaks open their seals blocking the doorway to Osiris.
The Guardian activates an Awoken Beacon
The Guardian enters the Ascendant Plane.
Reaching the exit portal back to the Dreaming City, the Guardian is confronted by Kelgorath, Risen from Bones.
The Guardian defeats Kelgorath and his allies
The Guardian steps through the portal and returns to the Dreaming City, beginning a cutscene.
Crow pauses and studies Mara's face.
Mara's eyes narrow but Saint-14 and the Guardian arrive before she can respond
"Osiris" steps backwards as he speaks and his voice begins to change, replaced by Savathûn's, who begins to transform into her true form to the horror of the Guardians.
Mara closes her eyes as shadows begin to cover the room, then holds out her hands while her eyes glow. A flash of light creates a cocoon around Savathûn, halting her transformation and entrapping her in a large crystal.