"A wizard cannot do everything; a fact most magicians are reticent to
admit, let alone discuss with prospective clients. Still, the fact
remains that there are certain objects, and people, that are, for one
reason or another, completely immune to any direct magical spell. It
is for this group of beings that the magician learns the subtleties of
using indirect spells. It also does no harm, in dealing with these
matters, to carry a large club near your person at all times."
-- The Teachings of Ebenezum, Volume VIII