Luna has been trying to resurrect Ur-Farah...and the Idigam are tools designed to help.It makes sense for Luna's, let's call it her idiom:
- The Moon is coneptually connected not only to change, but also renewal.
- Luna was presumably in love (or what passes for "love" among spirits) with Father Wolf, and being a spirit of renewal, it would fit in with her idiom to try and "renew" him.
- Resurrecting such a powerful spirit, however, would be no easy task, and may well be impossible.
- As a result, Luna may simply not have the power to manipulate a spirit's Corpus on that level. And what do we know as being basically the best at manipulating spirits? Idigam.