I'm doing it.
With 30% Crit:
On 4s Holy shock, the glyph is more mana until ~10k spirit.
On 6s, the glyph is only more mana until about 6.6k spirit
With 20% Crit:
On 4s, passed by 6.6k spirit,
On 6s, passed around 4.4k spirit.
Edit: Those values are under the assumption you hit Holy Shock on cooldown with mechanical precision. In practice the glyph is worse than listed.
Unless you're doing some sort of wonky low spirit-high crit build, it's going to be pretty difficult. And like Roakhar said it requires super precision on Holy Shock, which is not even near impossible, it IS impossible (unless you just don't cast anything for the last seconds of HS every time).
Mind you crit healing is a play style. It isn't spray and pray. The watch your op zero overwhelming mastery skyrocket past the Druid.
I'd maybe even recommend not using the glyph and just trying spirit/crit. I do it for a few fights and I honestly love it.
I don't use the glyph, its a gimmick. It's a tweak away from being godly/mandatory. So don't ever expect it to be changed. You really don't need that much spirit. Since you can actually use heals other than Holy Radiance. Since HL has like 50% chance to crit. I was getting 77K average HLs for 7k mana. Yes please.
Like I said, it is a play style. You cannot go and blanketeflolmastery2ez. You need to activity heal and watch for over healing. Your on command healing is better than haste and with all the critting mastery starts to become a 1:1 stat with crit.
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