Sorcery of Fadus

Apparently, there was a special sorcery that was used just by the Fadus. They say that the sorcery drained power from Nature such as Plants, Animals, Corpses, etc. However, due to the friendship between Ganelle and Vedir, there are more Fadus that now follow the Spirits, and so the sorcery of Fadus has been forgotten. They say that only a few Fadus can be used it now.