searched, couldnt find much.
i know this works for mages (me <3 )
might work for others. the debuff unchained magic stacks a buff on you when you cast a spell. 1 stack per spell, the more you cast, the more damage you take at the end.
here is the exploit.
you can get away with using instant casts straight after a casted spell and only take 1 stack.
mini example if that doesnt make sense:
i cast fireball = 1 stack
i cast fireball again = 2 stack
(yay, hot streak)
i cast fireball again = 3 stack
i cast pyroblast (spamming the crap out of it while casting fireball) = 3 stacks still.
enjoy!