So to add more, I found Golden Colored Funguars in Adoulin and Robel-Akbel opened with Thunder 5, followed by: Blizzard 5, Fire 5, Stone 5, and back to Thunder. So it seems that he will go for the highest Spell that he thinks will kill an enemy and progress down, until the timer is back up. Not as exciting as I'd hoped, but still leaves the question why he skipped Aero V in this instance.