Preparation:
It is suggested that there be no more than four people to a form.
Normal spell ups for each person, since hunters can blind and switch tanks. The tank should be able to take bolts, since archon hunter masters can do so. Plenty of reagents. If bolts can be cancelled, do so, and be prepared to spam 'cure light'.
Encounter:
Archon hunter masters can vary, but they are obviously significantly stronger than normal archon hunters. They can prevent fleeing, cast all the same spells as archon hunters can, but at an increased damage rate.
Loot:
Archon tokens, various scrolls, relics, gemstones. Just as masters vary, so does loot.