This page explains how to complete the level 85 Endwalker quest "At World's End".
Requirements
This quest is available if you have completed the quest Under His Wing.
Starting the Quest
Talk to the Radiant Host Soldier in Radz-at-Han to begin the quest.
Speak with the Radiant Host Soldier 1
Go northeast and through the door at the end, then go southeast down the stairs. Talk to the Radiant Host Soldier to proceed.
Attune to the Aetheryte
You can now attune to the Radz-at-Han Aetheryte, to be sure to do so before you proceed.
Speak with the Radiant Host Soldier 2
If you have attuned to the Hall of the Radiant Host Aethernet Shard, you can use the Aetheryte to go there. Otherwise, go northwest along the hallway behind Awareen, attune to the Aethernet Shard at the end of the path, then speak to the Radiant Host Soldier to proceed.
Speak with the Radiant Host Soldier 3
Go west through the door to reach the quest icon on the map. Talk to the Radiant Host Soldier to proceed. There will be a cutscene.
Role Quests
You can now speak to the delegates in this room to begin the Endwalker Role Quests. These quests are NOT required for the completion of the main story.
Speak with the Radiant Host Soldier 4
Talk to the Radiant Host Soldier to proceed.
Speak with Mihleel
Exit the room and use the Aethernet Shard to go to Mehryde's Meyhane. Go east to the quest icon on the map and talk to Mihleel.
Speak with Y'shtola
Go to the quest icon on the map and talk to Y'shtola to proceed. There will be a cutscene.
Speak with Thancred
Talk to Thancred to complete the quest.
Next Main Scenario Quest
After you complete the quest, you will need to be at least level 86 to proceed to the next quest. After you reach level 86, talk to G'raha Tia to accept the next quest: Return to the Crystarium.