Haste until 4204 > Mastery = Haste between 4204 & 19771 > Haste over 19771 > Crit
The 4204 point (3741 for Goblins) is a 1 second GCD with the haste aura and one 30% haste buff. 19771 (19154 for Goblins) is where 2 second casts will hit 1 second with the haste aura & one 30% haste buff. Again given the stat requirements to hit the second haste target (around 35,000 haste & mastery rating) so I doubt that will be practical for this expansion either. Again, a simplified version:
Haste until 4204 > Mastery = Haste above 4204 > Crit
An easy way to work out how much Haste and Mastery you should have is to add them together, subtract 4204 for that initial target, then divide by two. This will be your Mastery target, while your Haste target is Mastery + 4204.
Mastery Target = ( H + M - 4204) / 2
Haste Target = Mastery Target + 4204
Im thinking of trying it out. But currently i use a heavy haste build. Does this math work any different for me? Or still just 1+1-4204/2= ?