You are to rendezvous with Alphinaud at Snowcloak to be apprised of the plan to reach Iceheart's sanctum.
This quest is available if you have completed the quest A Simple Plan.
Starting the Quest
Talk to Minfilia in the Rising Stones in Revenant's Toll in Mor Dhona to begin the quest.
Speak with Alphinaud
Go outside and go northeast to reach the Coerthas Central Highlands, then go northwest to where the orange arrow is pointing in the minimap. Talk to Alphinaud and there will be a cutscene.
Speak with Alphinaud Again
Talk to Alphinaud to proceed.
Speak with the Stalwart Temple Knight
Talk to the Stalwart Temple Knight nearby.
Akh Afah Amphitheatre (Hard)
Use the Duty Finder to enter Akh Afah Amphitheatre (Hard). Please see the Akh Afah Amphitheatre (Hard) Guide for a walkthrough.
After you complete the duty in Akh Afah Amphitheatre and exit the area, there will be a cutscene.
Speak with Moenbryda
Talk to Moenbryda to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Moenbryda to accept the next quest: The Road Less Traveled.