Aggro, and what happens when you have it

Whenever you get into combat, monsters automatically create a "hate list". They will attack whoever is on top of that list (exceptions apply). Everything that you do in combat moves you higher on the hate lists (aggro) of each and every monster in combat, for example, drinking a potion, using Bloodrage, healing, dealing damage, etc etc. Monsters will attack you if you are right at the top of their hate list, unless you are

1) In melee range (5 yards I believe) and at less than 110% of the aggro of the guy the mob is currently hitting (tank)

2) More than 5 yards away and at less than 130% of the tank's aggro.

Therefore, if you are not the tank, you don't want to be at the top of a mob's hate list. Here's a nice list of the threat modifiers of each class if you're interested.

What we should be interested in, however, is what happens when the fit hits the shan and you pull aggro from me (or your tank). In patch 3.0.8, all player taunts were changed such that they not only work in melee range, but work up to a range of 30 yards, like for example, Taunt. What's going to happen when you pull aggro from a caster mob is that I will taunt it back, and continue building hate on it since it is casting a spell at you and wont move out of my melee range.

When you pull a melee mob, however, it will turn away from me, and walk towards you. What happens here, is that I will taunt the mob, expecting you to either 1) stop hitting it NOW, or 2) Feign Death, Vanish, threat wipe, etc etc, such that the mob walks back to me and I can continue hitting it.

I'm sure I speak not for myself, but for every other tank since Wrath, when I say that people who pull mobs away will continue hitting the mob, harder if need be. If you have played a tank and have been in such a situation, you know that the next thing that will happen, is that said mob, will walk back to you for 1 or 2 seconds, and then turn around and look for the DPSer who didn't stop attacking to bash his/her skull in. At this point, there is very little you (as a tank) can do except to move there ASAP and blow a second taunt, right?

Moral of the story: If I taunt a mob back to me, stop hitting it!

Of course, blowing a second taunt is not the end-all be-all solution, since warriors have many ingenious ways of handling such ridiculous nonsense *ahemBahemZ*. I thank the people who have so far managed to do what it takes to have the mob come back to me, such as K. When forced into such situations, however, you are forced to be creative to find ways to handle it...

For warriors:

As always, don't panic. At this point, your Taunt is already on cooldown, and the first thing you should do, is to check for your Charge cooldown. If it's available, Charge that offending DPSer mob, and introduce him to your Shield Slam and/or Revenge. If not, check your Heroic Throw. If it's up, use it. That should buy you a couple of precious seconds to let your Charge or Taunt come off cooldown. If Charge and Heroic Throw are both on cooldown, Intervene the mob, and you will charge towards that DPSer, and now, Concussion Blow or Shockwave it before pressing Mocking Blow to shift the mob's focus back to you, and finally Taunt it back when your Taunt comes off cooldown.

Certainly I don't expect you to master this overnight, so practice, practice, practice. Encourage your DPSers to pull aggro so that you can practice (within reason of course). Make sure your healer is symapthetic too.

For paladins:

Since I don't play a paladin, the best I can help you with (to my knowledge), is to hope the mob isnt too far from you, and use Hammer of Justice on it to stun it, and you should be near enough by now to bring it back under control. If that fails, use Hand of Protection on the offending party member.

For death knights:

If you used Death Grip to pull, and your Dark Command is now wasted used on that offending DPSer, you can either use Chains of Ice/Icy Touch on it, or if your frost runes are on cooldown and you don't feel like blowing your Empower Rune Weapon, feel free to sit back and watch that DPSer die. No I'm kidding =D. Why are you still reading this!? Chase after the mob and make sure it doesn't kill that idiot who pulled aggro!

And finally, for druids:

There's really not much you can do save for using your Feral Charge on the mob that decided the mage in cloth was juicier. If you used your Feral Charge to pull (shame on you!!) or have no rage for it, there's nothing else you can do except chase after the mob and Bash it while waiting for your Growl to come off cooldown, or use your Challenging Roar.

Hopefully, this will give you peeps an idea of what aggro is like, and how messy it can be when people pull aggro all over the place, and some ideas of how to handle it when it happens. For DPSers, if you are reading this, you now know that a tank's job is not just to sit there and take punishment, so do whatever you can to make his/her job that much easier. He/she will thank you for it.