This page explains how to complete the level 90 post-Endwalker quest "King of the Mountain".
This quest is available if you have completed the quest An Unforseen Bargain.
Starting the Quest
Talk to Alphinaud in Tertium in Garlemald to begin the quest.
Wait at the Designated Location
Check on the sparkling Destination to proceed. There will be a cutscene.
Speak with the Spirited Engineer
Go north to exit the train station, then go south to where the orange arrow is pointing in the minimap. Talk to the Spirited Engineer to proceed. There will be a cutscene.
Use the Duty Finder or Duty Support to enter Lapis Manalis. Please see the Lapis Manalis Guide for a walkthrough.
After you complete the duty in Lapis Manalis and exit the area, there will be a cutscene.
Speak with Y'shtola at Deepspine
If you departed from Deepspine, you can go to the quest icon in Garlemald to speak to the Spirited Engineer and return there. Talk to Y'shtola to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, talk to Varshahn to accept the next quest: A Dragon's Resolve.