My wizard tells me that she remembers reading something about being able to use thaumaturgy to determine the source of magic, but neither of us can find it in the book. How does this work, if it's possible, and where can I find it in the book?
edit- To give some more info. The idea is to be able to determine a physical direction of the source magic caster/s of a magic spell. This could be either during the casting of the spell or within a time period after the spell has been cast.