Hi all,

I would like to understand how aggro generated by healing does work in the case of multi-tanking. As I have not seen any study on this subject, I will simply talk about what I’ve heard and not what have been tested.

Let’s take a situation where there are several monsters, and some party members. The tank pulls, the healer heals the tank and other people who take damage, what’s next ?

1) Some people say that mobs share a common hate list, meaning that not matter who the healer is healing, he will generate hate on all mobs.
2) Alternatively, some people say that when he is healing someone, he will only generate hate on the mob which is striking the person he takes care of.
3) Another theory states that healing aggro is shared among the differents monsters (wowiki says something like 2*aggro/number of ennemies)
4) There’s surely other theories.

After some test, I believe that reality takes into account both 1 et 3 theory which are not exclusive.
Does someone ever bother to do some testing of this ? Can anyone help me before I start testing this subject ?


[edit] Ok all my answers are here : Kenco: A Guide To Threat.

I could be wrong, but I believe the well-accepted explanation is that healing aggro is divided evenly among enemy creatures in combat.

Non-CC'd enemy creatures, correct?

Not in my experience, assuming the even division theory. Moroes' adds come to mind off the top of my head, here.

I could swear I read somewhere here (and Moroes was the specific example I think) that while shackling itself causes a small amount of aggro, healing doesn't build hate with shackled targets.

I can say with near certainty that when a shackle breaks targets always run for me first UNLESS they were subject to some threat-building action before I shackled them. They may run to a different healer after the original beeline for me, but I'm pretty sure that's how it always works.

[EDIT] Here it is: How do uncontrolled pets work? (Shadowfiend, Searing Totem, etc)

I haven't done any real math on this so I may be wrong, but anecdotally, based on the ease at which a warrior can hold 4 mobs on him by doing nothing but spamming thunderclap while he's being chain healed, I'd say the threat gets divided evenly amongst the targets.

I'm reasonably sure I've pulled healing agro of a CCed mob before. You have to put out a lot of healing in a multimob situation to translate to meaningful agro, remember healing is half as much agro as DPS before talents, salv, being paladin, overhealing doesn't count, etc. Once you start dividing it between four mobs you really need some large numbers to pull agro.

It would be hard to test on simple mobs like servants in blasted lands since they don't do any meaningful damage to heal. Next time you're doing Aran, ask the warlock to note who the banished elemental is targetting when the banish fades.

e: I just remembered that there's something funny with agro of stunned mobs. I think you can build threat on them normally, but you can't taunt them, or have they fixed that?

For most fights, view threat as a list of playerID/threat/distance (and many more variables) attached to each mob. Damage does certain amount of threat, heal does another, special attacks (heroic strike, sunder, etc) do another amount. Some are fixed, some vary with modifiers (+damage, AP, etc). Every few ms a resort is done and a mob chooses a new target if certain conditions are met - the 110% over current target for melee, 130% for ranged, etc.

There is no shared hate list, otherwise every DPS class would pull hate on multi-mobs. Its unlikely there is a seperate damage/heal list, its just simpler to calculate "threat" and put in the damage/heal modifiers before the value is inserted into the list.

It is possible sheep/shackle/seduce/etc do not generate heal threat while they are CC'd (they obviously would generate aoe/dmg as that breaks CC). In fact, I pretty much guarantee this for seduce at least - if you cast CoS before seduce the mob will aggro you when seduce breaks. Otherwise it aggros the succubus. It won't aggro the healer, who obviously has generated lots of threat while the mob was seduced.

There is an issue (sometimes) with paladin taunt while a mob is stunned. It doesn't seem 100% (or maybe its been fixed?), but stunned mobs have no target, which makes it impossible for a paladin to taunt them, since our taunt (regardless of macros) is actually targeted on a friendly player.

So if healing agro was a problem in a raid encounter, just pull some weak trash mob and have it offtanked by a hunter pet and you'll only get half healing agro on the boss?
e.g. a whelp + Lashlayer

Provided your tank was in the whelp's threat list as well as Lashlayer's, yes.

I was convinced for the longest time that I was building threat on CC'd targets, until a hunter guildy disputed it and I started paying attention again. He'd trap something, I'd heal up a storm, stop before it breaks, and it would continue to go at the hunter. Same with sheeps, banishes, and probably everything else. Other forms of crowd control cause some amount of threat, and it appears shackle does too.

It didn't used to seem that way with the amount of times I'd get flattened by lava elementals that just broke banish or an Executus add that just broke sheep. I'm of the belief now that those were all due to the fact that most CC'd mobs have next to no threat at the time they are CC'd, and it takes a relatively small amount to pull them right after they break. It's very common to have a heal or renew tick land right as they break, which reinforces the misconception. It took me so long to realize it because previously if I noticed a CC break I would immediately fade, and if I didn't notice there was a mob in my face. Being able to throw a heal safely even when CC just broke is one of the truly marvelous parts of prayer of mending.

Kenco covers AoE heal threat in his thesis - linked here Kenco: A Guide To Threat.

Short summary, yes heal threat is divided evenly among all the mobs who have the heal target on their threat list.

While I hadn't thought about it before, the non aggro-building of CC'ed targets makes a lot of sense.

What do you do when you want to control a CC'ed target? Have a tank whack it once or twice, then start CC'ing. When the CC break, it will happily run after the tank. Works on Moroes, Oz, Houndmaster packs in Shattered Halls, etc. Heck, we use to do it at Garr.

The threat-splitting itself is pretty apparent to anyone who used Priest kiting at Gluth.

Split up between all non-CC'ed mobs that are in combat with your group/raid.

Nitpick question for my own curiosity: What exactly flags a mob as crowd-controlled? Apart from the obvious choices like Trap/Poly/Seduce/Sap, would effects like Gouge/Blind (Disorients) or Stuns (Kidney Shot/Cheap Shot) or Fears also temporariarly stop a mob from adding threat to players?

It's a dumb question, granted, but accurate knowledge on what characterizes "crowd-controlled" and stops threat generation could prove to be useful, even if not at large.

Just a thought, range from the healed target may have to do with it.
Try experimenting with CC'd mobs at different ranges.

This isn't 100% correct. A mob recalculates target only after threat changing moves from a player.

Are you sure about that? If you are number 1 on threat and you get a temporary deaggro such as fear or BoP the mob that was locked on you will turn to the next non-CCed player second to you in the aggro list. While doing any aggro move after the CC breaks on you (Battleshout, FFF etc) will cause it to turn back instantly just waiting for the mob to come back on it's own seems to work - but usually takes the mob longer to "realize" that you are back to be beat on.

I'm quite sure, that

#show Sunder Armor
/cast [target=mouseover, harm, nodead] Sunder Armor

did help me fairly well getting some aggro on sheeped/trapped/shackled targets while they are still cc'd without breaking it. Guess i have to test, if my macro is totally useless or not, assuming they dont generate aggro while crowdcontroled.

While the initial assumption about AoE healing threat is correct. That threat is divided by number of mobs. I'm pretty sure the threat-distribution is only shared between targets you currently have aggro on. I don't have any concrete data to support this, only anecdotal evidence.

The most obvious was from Uldaman, on the 5-6 "normal" golem groups in the room with the 4 guardians. As a warrior, if i just went in, spammed thunderclap, shouted a bit and started dishing out sunders, they would all stick to me, and never bother the healer. However, if the mage started AoE'ing, he would pull 2 or 3 of them pretty quickly, while those remaining on me, would beeline for the healer.

The story would be: I pull, take damage from 5 mobs, so health dropping merrily, mage gets aggro on 2-3 mobs who hadn't gotten sundered yet, large heal lands on me, at least 1 of the remaining mobs head for the healer. If we just single-target dps'ed them down, all of them except the dps target would stick to me.

On a side note, i don't recall pulling aggro on a mob while healing someone they weren't tanking, but it's been a while since last i've been healing much, too much tank shortage.

Theory #2 is definitely false, I was MT healing on Maulgar last night and got smacked in the face by Olm repeatedly.

As to establish whether or not healing aggro is shared between all mobs you are in combat with, or all mobs that the heal target is in combat with, try this test: bodypull a mob, have a tank-type taunt it off you (0 threat) and stand there doing nothing. Now heal someone else in a seperate fight somewhere nearby. If you get the first mob you know your healing aggro is based off your combat list, if you don't it's based off your target's combat list. I'm not sure that really matters overmuch, because I can't think of any situations it's really relevant, but it's an interesting theoretical exercise.