I thought I’d cover something so widely recognized by players, but not completely understood. This is of course, threat and aggro.
We’re all used to the idea of making sure the tank keeps aggro in our raids. On the face of things it seems quite simple: make sure the tank has more threat than everyone else. However, this isn’t actually 100% correct, as there are a few more details behind the curtain than you’d first suspect. But firstly, let’s talk about how threat is generated.
For damage, it breaks down to a very simple 1:1 scale: 1 damage equals 1 threat. If you hit an enemy for 3,000 damage, that’s 3,000 threat. As a side note, Patch 3.0 changed it to 1 damage = 100 threat. The reason for this change was to avoid slow floating point computation and instead use less computationally expensive integer calculations. However, this change only changes the internal workings and a 1:1 ratio generates the same results and theory.
For healing, it breaks down to 2:1 (or 1:0.5). This means that for every point of healing done, the healer will generate half that as threat. A 5,000 heal will mean 2,500 threat. This threat is of course spread amongst all the enemies in the current combat. If there were 2 enemies with the previous example, the healer would get 1,250 threat on each enemy. Although this sounds like the healer will have a lot less threat because the coefficient is much lower, healers are generally healing a lot more than you are dealing damage. Of course, there are class and spec specific modifiers to these threat calculations.
This all sounds simple enough, but there is one more thing to consider. Most people assume that having more threat than the tank will cause you to pull aggro. This isn’t actually true. To pull aggro from a tank, you actually need 110% of the threat of the tank if you are in melee range. To pull aggro at range, you need 130% threat of the tank. This is one reason why classes such as Hunters and Mages should always use their threat clearing abilities often, and not just when you’ve pulled aggro. Here’s a simple scenario to illustrate why:
We have the following threat table during a boss fight:
1st Warrior Tank 1,000,000 threat
2nd Hunter 1,250,000 threat
3rd Elemental Shaman 1,220,000 threat
4th Priest healer 1,150,000 threat
Although the Hunter, Elemental Shaman and Priest are above the tank’s threat, they are still under the amount needed to actually pull aggro. Now, if the hunter pulls aggro, the boss is going to come to him and munch his face off. No problem, the hunter has feign death. The problem however, is that the boss is now in melee range of the Elemental Shaman and Preist. To pull aggro in melee range, you only need 110% threat. This will cause the boss to aggro to the warlock and the preist, munching their faces off and in all likelihood, cause a wipe.
This is one of the main reasons why you need to be aware of pulling aggro. You may well have a threat dumping ability, but it can still cause the boss to destroy the rest of the raid should they come into melee range.
Of course, in a raid you shouldn’t ever pull aggro as you should threat dump early and often.