“Mission Captis” comprises the 15th and 16th step (of 18 total) in the “Act 2: Rites of the Deep” quest for episode Heresy.

Sundered Doctrine, the dungeon from Episode Heresy in Destiny 2 takes players back to Rhulk's Pyramid ship in Savathun's Throne World. However, with Rhulk defeated back during the Vow of the ...