Spellbook Seller Elena:
According to the book, the Archon of Halisha is very patient.
You can find him inside the Four Sepulchers. To enter, you must form a party.
If you choose to fight alone, slaughter the Archon's minions at the Shrine of the Loyal. Collect 700 of Halisha's Marks and he will appear.
Halisha's minions are Grave Scarabs, Scavenger Scarabs, Grave Ants, Scavenger Ants, Shrine Knights and Shrine Guards.
After you get the Resonance Amulet, find the tablet on the way to Goddard from the Wall of Argos.