General guideline is nothing should be provoked except the spiny. Obviously in first phase you can pull sub off MT, but in Tornado phase this really isn't necessary.

P.S. to make this whole fight a helluva lot easier take 1 healer. The extra dps means you only have to do the tornado transition 2-3 times instead of 5-6.
It also means you can afford melee to just stand around instead of running in on Sub during tornadoes, ect. There is no reason for 2 healers on this fight.