I've found threat mechanics to change quite drastically from the first 3 up to qarn now, in the first 3 dungeons I would lob, flash flash then fast blade > riot blade > flash until mob 1 was dead then switch off to mob 2, repeat and by mob 3 no more flashing required so fast > savage.

Now I find that flash agro is garbage except for initial agro to keep off healers while I rotate my higher agro skills in on the mobs, so now its lob, flash flash flash, fast > savage > rage on mob 1, fast > savage mob 1, rage mob 2, fast savage mob 3, back to mob 1 rinse repeat