[Faceman]

There are two of these jewels
One you get from the pedestal near Mazzy and the Shadow Jailor. It is used to dissolve the first wall of shade and disappears after that.
The second you get after crossing the Indiana Jones floor and it is used for the third shadow wall (the second you can bypass by a short trip to the lava)
The assembled Symbol of Amanautor you need to open the door at the end of the level and the Shadow Dragon Wardstone is there just so you don't get attacked right away by the ..ehm.. Shadow Dragon.