High Priest Gregory:
Get your next Stone of Commune from the Archon of Halisha inside the Four Sepulchers. You must form a party before you attempt this!
If you have trouble forming a party, go to the Shrine of the Loyal and attack the Archon's minions. Their deaths will provide marks of Halisha. Collect 700 of them and the beast himself will appear!
Halisha's minions are known as Grave Scarabs, Scavenger Scarabs, Grave Ants, Scavenger Ants, Shrine Knights and Shrine Guards.