TL;DR

For our regular heals (pretty much everything that PW:S), you want to be keeping your crit percentage, after all buffs, about 7-8 percentage points ahead of your mastery. The more precise formula to follow would be:

C=0.11+0.9M




If your crit is more than that related to you mastery, then you want to increase your mastery; if it is less then you want to increase your crit. Given that we already get a large percentage of mastery for free to begin with, this implies that crit would be a better way to go gearwise, until we reach high crit levels.

On the other hand, when considering PW:S mastery is still way ahead of crit, the optimal relation between the two being given by the formula:

M=0.3+0.8C




Which essentially expects mastery to be around 25-28 percentage points ahead of crit. As our PW:S will be a considerable part of our healing, this would seem to indicate that mastery and crit are very close to each other stat-wise. So to finally conclude this long post, the main 2 things to take away are:

  1. Crit and Mastery are fairly close to each other and we’ll want to keep them close to each other, with crit a few percentage points ahead if we don’t cast many PW:Ss, and mastery a bit ahead if we are into heavy PW:S spam.
  2. The difference between a crit heavy build and a mastery heavy build is so small, in the order of 2-3%, that for all practical purposes you can go with whatever feels best.
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