Operation Elbrus
While you await Caiatl's arrival, gather Psychogenic Intel to confirm that you stopped the Lucent Hive ritual.
Gather Intel by completing "The Witch Queen" campaign missions in the Throne World.
Intel can also be found in public events, strikes, Crucible, Gambit, and other activities.
Despite the situation in the Psisorium, the mission comes first. Gather Psychogenic Intel to confirm the Lucent Hive ritual was stopped.