I've been avoiding mastery (Illuminated Healing) on my gear for a while. Skada was estimating my mastery at less than 5% of a boost to my healing, as opposed to the extremely visible boosts that critical strike and haste offer. I figured, without the math, that with only our direct heals causing the bubble, and with the duration being short enough that not every bubble gets absorbed, it's going to be a pathetic amount of healing.
And at first glance it is, because Beacon of Light, Protector of the Innocent, and Holy Radiance don't cause bubbles, and those account for a brickload of my healing.
First, the log: WoL report for Four Lights Conclave Kill
Second, some rough math. I added together all my direct heals, including overheal. We're including on this list: Flash of Light, Holy Light, Divine Light, Word of Glory, Light of Dawn, and Lay on Hands (though I didn't cast any FoL). That's total effective direct healing of 1,302,129 and total direct raw healing of 1,451,189.
Third, my mastery. Like I said, I've been avoiding mastery when possible. According to my armory, I am currently carrying 8.89 mastery rating (8 base, .89 from gear). Each point of mastery rating adds 1.25% to each bubble. 10 base +(.89*1.25)=11.1125. So, each direct heal should in theory proc a bubble of 11.1125%.
Total raw direct healing of 1,451,189 should proc 161,227 in bubbles.
According to WoL, I had potential absorbs of 161,000 (listed to the far right as Overhealing). So my napkin math and WoL haven't disagreed too much there. Below, I am using 161,000.
However, in practice, I only had 105,818 absorbs via Illuminated Healing, or 65.73% of total potential bubbles. 55,182 (34.27% of every bubble) went to waste. Instead of enjoying 11.1125% absorbs, it's practically closer to 7.3%. Which isn't actually as bad as I had imagined it before, though still nothing to cheer about. WoL ranks Illuminated Healing as 3.9% of my healing because a good half of my heals don't proc it.
Tank Healing And Mastery
If what I've done above isn't convoluted enough, I decided to take a look at absorbs on just the tanks. After all, if Mastery helps us be better tank healers, then it's still a good stat. However, to do the modeling, I had to take a look at all holy paladin heals on each tank, all effective absorbs on the tank, each paladin's mastery, and extrapolate potential absorbs (the things I do for WoW...)
However, what I found is that (and here's a shocker) since most of our direct heals our going to the tanks, most of our wasted bubbles are on the tanks (68% effective, compared to almost 66% overall).
In summary, I am going to keep my eye on my mastery in other encounters, but crit, spirit, and haste are going to offer me far more healing than Mastery (can and) will.