Orphan has seen magic increasing or lowering at a regular frequency, or 'rotating' through other dimensions at a frequency. Fancy wizards do it quite often, in the fraction of the second they last before Orphan blasts right through them without any of that fancy stuff.
Falash means--something, possibly, to Orphan's memories, though it's not a word Orphan's memories ever recall hearing, the word is pointing to a thing the same way that 'type theory' points to something in Opalyn's memories without Orphan or Opalyn having ever heard the Eldric for it? It has a sense of it of compactness, maybe, of tight packing, like (now Opalyn's memories) a molecular crystal in which positive and negative charges on the atoms form a neat packing order and thereby closely align.