There is a book in there (don't recall where) describing what to do with the amulets, at least in general. If you use the 3 amulets in the proper place and order, you get the amulet of the north, with Wisdom +2, 3 enchantment slots IIRC, and other random bonuses. Specifically;
You must use the amulets at a well lit statue in the central area of the tunnels (in a room at the top of some stairs, with one wall being made of bars or a grating). You need to use the west amulet first, then east, then south.
