Actually, in the armoury, once you hit the button/switch in the fire room to unlock the door and reveal the scrying stone, there are 2 ways to get into the dungeon. The best method is to use the scrying stone from your inventory (after you pick it up), and you will end up inside the dungeon. If you return the scrying stone to the priest inside the village, wandering around beside the church, without looking into it, he will take the stone into the church and look into it himself (and be teleported to the dungeon). After that, if you enter the church you will get a quest talking to one of the parishioners to find out what happened to him. Either way, the use of the scrying stone unlocks the door.
