Originally Posted by
otaXephon
It depends on personal preference and your playstyle tbqh. Mastery is going to do better on any fight with sustained AE (Wind Lord, HC Sha towards the end) while Haste is generally a better stat for maintained single target DPS. A Haste-focused build also works well if you ditch EB for PE (which has an added benefit of simplifying your rotation a bit). Additionally, a Haste build with EB would also likely situationally perform better, as well, but the general consensus from a purely min/max standpoint is to take your gear, sim it, and find out what works best.