I'm reminded of the amusing sidebar in the RPG Unknown Armies, which uses the -mancy suffix for all of its magical schools.

Technically, the various schools of magick - Dipsomancy, Pornomancy, etc. - should actually be written out as Dipsomagy, Pornomagy, and so forth. The suffix "-mancy" refers to magickal divination, whereas "-magy" means more general forms of magick. Even more technically, a more etymologically correct suffic would be -"urgy", giving us Dipsourgy, Pornourgy, etc. Regardless, "-mancy" is what passed into common currency among the new wave of adepts, and the occult underground is stuck with it - the way normal folks are stuck with people who use "orientated" when they should use "oriented", or who use "literally" when they shouldn't use anything at all. Old-school occultists and scholars tend to make a point of using either "-magy" or "-urgy", which makes novice adepts look at them funny. Life goes on.

(And yes, Pornomancy is pretty much what it sounds like. For maximum weirdness, see also pages 14-15 of this preview PDF. Unknown Armies is awesome.)