Heroic Megaera’s Diffusion Mystery
EDIT: I updated the numbers in the post following the excellent comments by Vixsin and Lakh. I have very little background with this sort of thing, so the help is very appreciated! I hope no one read the post expecting revelations and great number gymnastics. I’m only a curious healer who tends to fixate on minor details and who doesn’t turn away from a challenge. I have no answers myself, but there are some great comments in the comment section for those looking for information.
Ever since I stumbled across a parse where I randomly did 5 million healing from Diffusion, I’ve been fixated on figuring out how that spell works.
Sadly, after hours and hours of pulling my hair out, I still don’t know.
In theory, Diffusion (available only on Heroic mode) is a debuff the Arcane Head puts on anyone who gets hit by its Arcany breath. The debuff redirects 10% of healing received to targets within 8 yards. It also stacks, which, if I understand right, would redirect 30% of healing received.
In practice, it is certainly a debuff put on Breath takers by the Arcane head that causes nearby players (and pets) to get healed, but how exactly it works is a still a mystery to me, even after I’ve gone nearly bald going through logs.
Anyone who, following this post, has further insight, is welcomed to share it. I’m happy to provide links to the actual logs if anyone wants to give it a go for themselves as well. Maybe I’ll finally get some closure and be able to move on with my WoW life.
Who Had Stack of Diffusion?
As you can see here, both our tanks and only our tanks were affected by the Diffusion debuff.
A Look at Our First Diffusion
For visual types, here is the uptime of Theck’s Diffusion. Let’s select approximately that period of time for the Log Browser.
Aaaand the queries used.
Theck was my Beacon target and I wasn’t sure if Beacon could trigger diffusion so I included it. I realized as I was doing this writeup after hours of taking screenshots of my logs that I probably should have included Arcing Light, Holy Radiance and Daybreak. I really don’t have it in me to redo all my shots (I’m embarrassed enough about the amount of time I’ve wasted on this one, useless detail of a spell) and these heals are unlikely to be relevant, but I’ll add their lines in by hand. And if anyone thinks I’m making up the weirdness of Diffusion, they’re welcome to have a look at my logs themselves.
So for the first tick of Diffusion.
Beast got a nice overheal of 19556.
Since it was shortly after the third stack of Diffusion was applied and we can leave some room for delay, we should consider that the heal could have procced off two stacks, or off three. The heals needed to proc a Diffusion heal of 19556 are:
If 3 stacks (30%): 65187 – 19556 (absorbed) = 45631
If 2 stacks (20%): 97780 – 19556 (absorbed) = 78224
Or if Beast’s Hunter is glyphed, the Diffusion heal should have actually been (19556 * 0.9) = 17600
If 3 stacks (30%): 58667 – 17600 (absorbed) = 41067
If 2 stacks (20%): 88000 – 17600 (absorbed) = 70400
Even assuming that Beacon and overheals can trigger Diffusion, the only value in that ballpark is a 40k overheal at 21:49:40.190.
Let’s look at the next tick of Diffusion.
The screenshot got cut off because I was only interested in the Diffusion value, but I should probably add that most of the raid was healed for the same thing as me, 22874. (Yay for Diffusion during Rampage!)
Also missing on the screenshot (after adding Daybreak, Arcing Light and Holy Radiance) are:
[21:49:59.476] Rykga Arcing Light Theck +3242
[21:50:01.550] Rykga Arcing Light Theck +3291
[21:50:01.550] Rykga Holy Radiance Theck +3303
For a 22874 tick at 3 stacks of Diffusion (30%), we would need 53373 (which is 76247 – 22874) healing.
The only thing that would come somewhat near that is:
[21:49:45.859] Rykga Beacon of Light Theck +41980 (O: 43649)
But, again, this is assuming Beacon triggers Diffusion. And that a whole 15 seconds delay on the tick is normal. And that we’re off by 12k.
Another theory would be that healing done accumulates on a target and is released at once later on (after all, the Diffusion description reads “all healing“). We can look into that, but let’s choose our other tank, the one who isn’t getting 23948723894 heals from Beacon of Light.
This is the uptime from our tank who took Diffusion stacks later on in the fight. Let’s select this part of the fight for our Browsing pleasure.
And the first tick!
There were no extra heals from Arcing Light/Daybreak/Holy Radiance.
One tick of Diffusion on Beast for 13692. Agwyne clearly had only one stack of the debuff (10%), meaning that we would have needed a 123228 (136920 – 13692) heal to trigger this.
Or if Beast’s Hunter is glyphed, then the Diffusion tick was originally 12321, meaning it would have needed 110889 (123210 – 12321).
Lay on Hand was too powerful and nothing else even came close. I calculated the cumulative healing between the Diffusion application and the Diffusion trigger, giving me a total of 94416, excluding Lay on Hands, a number that isn’t quite there. So that theory doesn’t work either.
Onto the next tick.
Again, it’s unclear if the tick on Beast came from 1 or 2 stacks of Diffusion, so considering either possibility, to get a heal of 10554/9499, we would have needed 94986/85491 for one stack (10%) or 42216/37996 (20%).
There was one Eternal Flame for 82305, which, I guess, is pretty close, but there is a 10 second delay.
One final chance!
Including the extra spells, we’ve got:
[21:53:43.792] Agwyne afflicted by Diffusion (3) from Arcane Head
[21:53:44.134] Rykga Holy Shock Agwyne +*78504*
[21:53:45.790] Rykga Divine Light Agwyne +*140007* (O: 744)
[21:53:45.856] Rykga Eternal Flame Agwyne +0 (O: 7316)
[21:53:48.235] Rykga Eternal Flame Agwyne +*15071*
[21:53:50.731] Rykga Eternal Flame Agwyne +0 (O: 7316)
[21:53:51.466] Rykga Holy Shock Agwyne +*0* (O: 78211)
[21:53:54.714] Rykga Holy Radiance Agwyne +0 (O: 17016)
[21:53:55.105] Rykga Eternal Flame Agwyne +*0* (O: 134561)
[21:53:57.153] Rykga Eternal Flame Agwyne +0 (O: 7316)
[21:53:57.889] Rykga Arcing Light Agwyne +*0* (O: 11355)
[21:53:59.235] Rykga Eternal Flame Agwyne +7316
[21:53:59.969] Rykga Arcing Light Agwyne +3551
[21:54:01.279] Rykga Holy Radiance Agwyne +3630
[21:54:01.340] Rykga Eternal Flame Agwyne +7316
[21:54:01.855] Rykga Arcing Light Agwyne +3493
[21:54:01.964] Rykga Diffusion Rykga +39217
[21:54:02.307] Rykga Diffusion Astart +39217
For a Diffusion heal of 39217 at 3 stacks, we’d need a trigger heal of 91506.
The Eternal Flame at 21:53:55.105 (134561) overshoots by 40k and is all overheal. There was an effective heal of 140007, but that was a good 16 seconds before the actual proc.
Alternatively, if you add up the preceding heals, you get 40377 between the Diffusion and 21:53:48.235.
There doesn’t seem to be an obvious way Diffusion works.
It doesn’t only trigger off big heals since none of my large Diffusion heals were triggered by a single heal. Nor do the heals from a single healer add up over a few seconds to be released at once.
The only other theory I could think of (other than the Diffusion heals being completely at the mercy of an RNG with a sense of humour) is that all heals (from all healers) on a Diffusion tank accumulate for a few seconds, then are released and attributed either randomly to a participating healing, or to the last healer to contribute to the Diffusion heal pool. (If you remember the odd healing attribution from Judgement of Light from back in the day, that is what this reminds me of.)
But as curious enough as I am, I’m not quite motivated enough (at this time) to investigate that theory.
Regardless, my statement from the Megaera logs post still stands:”Because Diffusion seems to only heal when it feels like it, without involving much control from the player, when analyzing logs and comparing my performances, I’d subtract Diffusion healing from my total healing count.”
Oh, and last raid week I did try tracking Diffusion on my frames to squeeze in as much healing on the tank as possible. What to see what happened?
(Note, I totally forgot to swap from Holy Prism to Light’s Hammer again. *fail* This is why I can’t have nice things.)
Not even a million! Diffusion works better when you’re not trying.