This page explains how to complete the level 83 Endwalker quest "Alea Iacta Est".
This quest is available if you have completed the quest No Good Deed.
Starting the Quest
Talk to Jullus in Garlemald to begin the quest.
Speak with Marcellinus and Octavia
Go to the quest icons on the map and talk to Marcellinus and Octavia to proceed.
Speak with Jullus
Go north to where the orange arrow is pointing in the minimap. Talk to Jullus to proceed.
Wait at the Specified Location
Go southwest to where the orange arrow is pointing in the minimap. Check on the sparkling Destination, and say Yes to proceed. There will be a cutscene.
Speak with Lucia
Talk to Lucia to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Lucia to accept the next quest: Strange Bedfellows.