Excuse me for saying the bleedin' obvious, then, but
if Mr (or Ms) Pyrrhic could find just one caster with a
lower ID than the opponent he could be sure to "surround" him?
As for "It's essentially random.", randomness is a bit of a hobby of mine, here the overall order is not at all random, though I suppose it is for the purpose of which direction it goes

Assuming that thejeff is correct (and I would not doubt it!), if that is the definition of the manual's "in a
random order", I wouldn't go basing an encryption algorithm on it
