Just as Minfilia and the Scions are about to make their grand entrance to the banquet, Momodi requests your presence at the Quicksand.
This quest is available if you have completed the quest A Time to Every Purpose.
Starting the Quest
Talk to Minfilia near the Chamber of Rule in Ul'dah to begin the quest.
Speak with Momodi
Use an Aethernet Shard to go to the Adventurers' Guild. Go to the quest icon on the map and talk to Momodi.
Rendezvous with Alianne
Go north to exit the Quicksand and go through the gate to Central Thanalan. Go northwest to where the orange arrow is pointing in the minimap. Check on the sparkling Destination.
Check on the sparkling Destination again.
Pick Up the Clouded Vial
Check on the sparkling Faint Light. 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.
Show the Clouded Vial to Momodi
Go southeast and enter Ul'dah. If you entered through the Gate of Nald, you can go south to enter the Quicksand. If you entered through the Gate of Thal, you can go north to the Aethernet Shard and use it to go to the Adventurers' Guild, then go southwest to enter the Quicksand. Go to the quest icon and talk to Momodi to hand over the clouded vial and complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Momodi to accept the next quest: The Parting Glass. 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.