This page explains how to complete the level 90 post-Endwalker quest "Shadowed Remnants".
This quest is available if you have completed the quest In Search of Azdaja.
Starting the Quest
Talk to Varshahn in the Fell Court of Troia (accessible via Thavnair) to begin the quest. There will be a cutscene.
Go southeast and talk to the Feral Voidsent, then go east and talk to the Watchful Voidsent, then go south and talk to the Forlorn Voidsent and the Fearful Voidsent.
Wait at the Designated Location
Go southeast and check on the Destination to proceed. There will be a cutscene.
Search for the Clever Voidsent
Go west and check on the Passage to Troia Keep, and say Yes. Go south and follow the path to the end, and check on the passage to Carcere IV, and say Yes to proceed. Go west and follow the path until you reach the orange circle on the map. Go into the cell and approach the Clever Voidsent. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.
Speak with Y'shtola
Talk to Y'shtola to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to the Dark-robed Voidsent to accept the next quest: Where Everything Begins.