Find the moon fragments on Lagon’s Isle.
You have traveled to Lagon's Isle hoping to reason with Architect Liath or to speak with Lagon directly.
When you entered the Moonlit Shrine, Architect Liath appeared and told you that she has no intention of letting you speak with Lagon. She also broke the mechanism that would allow entry into the temple.
Search the different areas of the island for the missing moon fragments that may reactivate the shrine's altars. You may find them in The Strand of Storms to the west and The Coral Pools to the east.