Master Tobald:
There are two ways to confront the Archon of Halisha. The devil has the fifth Resonance Amulet.
If you go to the Imperial Tomb, you'll find him in the Four Sepulchers. If you go to the Shrine of Loyalty, you must slay many of his minions for the Archon to appear.
This is all I can tell you! If you run into me later, don't bother me!