Theorycraft for “pure” direct spells says a direct spell’s coefficient is (cast_time)/3.5, using untalented cast-times. Instant-casts use a “cast-time” of 1.5s. HT and SF both get 100%. Wrath gets 2/3.5 = 57.1%.

Theorycraft for “pure” HoT/DoT spells says the coefficient is duration/15. Rejuv gets 80%. IS would also get 80%, but it is “penalized” 5% because in addition to doing damage, it applies an extra debuff to the target. As a result IS gets only 80%*95% = 76%.

For hybrid spells (MF, Regrowth) the computation involves two steps. First compute the coefficients for both parts as-if they were pure spells:

Direct
MFA = 1.5/3.5 = 42.9%
MFB = 12/15 = 80%

RgA = 2/3.5 = 57.1%
RgB = 21/15 = 140%

The coefficients then get reduced by a proportioning rule. wowwiki (http://www.wowwiki.com/Formulas:Plus_damage_and_Plus_healing) currently says the proportioning rule is based on the numbers above meaning

MF direct = MFA * MFA/(MFA+MFB) = 52.1%
MF dot = MFB * MFB/(MFA+MFB) = 15.0%

Rg direct = RgA * RgA/(RgA+RgB)= 16.6%
Rg hot = RgB * RgB/(RgA+RgB) = 99.4%

The MF numbers look pretty good, but as you pointed out, the Rg numbers are way off. Elitist Jerks says the correct proportioning rule is based on base damage, not time. That means

MF direct = MFA * 331/(331+600) = 15.2%
MF dot = MFB * 600/(331+600) = 51.6%

Rg direct = RgA * 1285/(1285+1274) = 28.7%
Rg hot = RgB * 1274/(1285+1274) = 69.7%

Those numbers look pretty good for both spells. Maybe if your +heal is high enough, you can tell if the Regrowth ticks are using a 10% or a 69.7%/7=9.957% coefficient.

Note that some spells just seem to break the rules. Lifebloom doesn’t seem to fit at all, although pre-nerf the bloom coefficent was pretty close to what you’d expect from an instant cast direct heal (1.5/3.5 = 42.9%).

I love your writing. It is the only resto blog this featherkin reads on a regular basis.

Over 100 casts, my low was 1984 and the high was 2135. This is with my +1602 healing, and every healing talent you can get (1/0/60 here).

Two things that I found really interesting while casting was how often I was getting a critical heal, and the proc of my t4 bonus. It took me 407 casts to get 100 non-critical heals. That’s with 5/5 Improved Regrowth, but still that’s much better than the 50% I was expecting (I have only a 10.93% base crit bonus).

I wasn’t so excited to see that in those 407 heals, I gained the 120 mana from “infusion” from my t4 2-pc bonus set only 7 times. At one point I had 76 casts in between infusions. At only 120 mana per infusion, I’m not going to lose much sleep when the decision to replace t4 pieces and lose that bonus comes up.

@Nebelmond: You rock. Thank you for this addon. I can’t wait to try it out for myself!

@Kalaghan: Thanks for the correction! I’ve edited the post.

I wrote a quick-and-dirty addon for the PTR, which counts your non-critical regrowths and calculates the healing coefficient. Feel free to download it here: http://81.169.188.141/RegrowthCoefficient.zip. Just type “/rc show” after a few Regrowths to see its values in your default chat. This should simplify the data gathering.

At 1847 +Healing on PTR Build 8031 my coefficient is as follows:
With no talents at all: ~0.29
With 5/5 Gift of Nature: ~0.39
With 5/5 Gift of Nature and 5/5 Empowered Rejuvenation: ~0.45

Anyway, I’ve always found regrowth extremely useful and this makes it even better. I hope those few regrowth-phobics still walking around with HT spam will now see the light and embrace the spirit of the tree

It does seem that WoWWiki should be corrected. The relevant number in my mind will be one with all the numbers included since you can’t break them apart in a predictable manner (particularly Empowered Rejuvenation).

It would seem that with all the relevant talents (GoN, Empowered Rejuv, Imp. Regrowth) figured in, the coefficient comes out to 0.5941. Without these included, it’s around 0.3592. Things are looking good for Regrowth. Still, why couldn’t Blizzard just make all this easy with a handy tab in your character sheet that breaks all this down? ^_^