In the castle area, right after engaging the Bugs in the sewers, you will see a large group of Ganados Zealots in mid prayer. If you spook them they will run away, and you miss out on ALOT of money. Right before the sewer they give you a flash grenade. SAVE IT. When preparing the ambush on the congregation, go north then swing across the chandelier. When on the other side look down, and try to hit them all with a flash grenade to stun. Immediately jump down and run north to their exit point so you lock them in. If you have an incendiary or frag grenade you could use it here, other wise line them up for some shotgun carnage. They will each drop a spinel and their leader drops an Illuminados pendant, worth around 32000 altogether.