If you perform an action on a nightmare monsters in Dyna in the time frame prior to that action being able to proc it, then it rolls over into that time, that action has a chance to proc it. For example, if you were to use a job ability on a monster while it is the magic proc time frame, then it rolls over into the time frame for JA procs, that job ability you performed earlier might proc it.
@Lakshmi.Vlorsutes
Ah, that's what it is, huh? Yeah, the proc times did change almost immediately after I fired off that Chi Blast, then a few seconds later it just procs out of nowhere.
And yeah, that's my quick shot WS macro for Asuran Fists.