This is a combination of a "Hard and Fast" guide and a fairly in-depth guide. I won't go to Elitistjerks levels, or even some of the more advanced tankspot guides (though I draw on them as a source and I recommend that you all read them) but it will cover more than the very basics.
What is threat? Threat is a measure that the game uses to tell who the mob will attack. If you have high threat on an enemy, the mob will attack you. If you are highest on the "Threat list" and the mob is attacking you, you "Have aggro".
Threat is a bit of a fickle stat, though:
How does it work?
Why is it that a dps class does three times the damage but I still maintain aggro?
What abilities generate a lot of threat?
How can I improve it?
To start, 1 point of damage = 1 point of threat. 2 points of healing = 1 point of threat. This is before ALL modifiers, and the modifiers are so significant, that it should really be taken with a grain of salt.
Additionally, global threat is divided between all targets, direct threat only increases threat levels on specific targets. Now, by "all targets", I mean all targets in combat. If a healer heals, it won't increase the threat on the mobs standing around at the far end of the hall. It WILL increase the healer's threat on all targets in combat with the group, but not by much. You see, if (say) a priest gets off a 10k heal and there are 5 mobs, consider it like this:
10000/5 = 2000 per mob
.5 threat per point of healing,
2000/2 = 1000 threat per mob.
If the priest has Silent Resolve, then multiply that number by .8, so the priest will generate 800 threat on all 5 mobs in combat--which really, is not much at ALL, when you consider these numbers:
I, as a warrior, Thunderclap these 5 mobs for (say) 500 damage each. No crits, no variance for simplicity. Because damage is direct threat, I gain 500 threat on each mob, which is not enough to take them off the priest healer. He dies. Or does he? Answer: No, because I didn't gain *just* 500 threat. I got a lot more due to threat modifiers.
According to wowwiki.com, the threat modifier on Defensive Stance is 2.0735, and the modifier on Thunder Clap is 1.85. This means, 500 damage done...
500 x 1.85 (TC's inherent modifier) = 925 threat
925 x 2.0735 (Defensive Stance's inherent modifier) ~ 1918 threat
Which puts me well ahead of the healer. The mobs attack me, the day is saved.
Many tanking abilities have inherent threat modifiers or additions. For example, Shield Slam causes an extra 770 threat in addition to the threat from the damage done (then multiplied by Defensive Stance). A druid's faerie fire, even though it does no damage, causes an innate 638 threat (which, if in Bear Form, is multiplied by 2.0735). A paladin's Righteous Fury increases threat from Holy spells (their main way of getting threat--Consecrate, etc) by 90%. A death knight's Frost Presence has the same modifier as Warrior's Defensive stance, as does a druid's Bear Form.
*Remember: Abilities that are AoE, such as Thunderclap, Consecrate, and Howling Blast: They do damage, which means they deal direct threat. BUT: Some abilities such as Demoralizing Shout ALSO do direct threat (unlike Battle Shout--which does generate a bit of global threat) even though they have no damage component.
This is because Blizzard has cleverly put in another stopgap between those DPSing and those tanking (but which can make your job slightly more difficult). Mobs need a little extra push to actually switch targets. By a little extra push, I mean your Bladestorming Arms Warrior friend has to generate 10% more threat than the target the mob is currently attacking for the mob to actually attack him.
"But there's this one Warlock, right? He does wayyyyy more damage than me, and even accounting for my threat modifier, he should out-threat me. As a matter of fact, if I look at my threat meter addon, he DOES out-threat me!"-Guy Learning About Threat
If you've put out 10,000 threat and he's just put out 10,900: you are In The Clear.
This is even more noticable with ranged classes. If the above Warlock is out of melee range, he must do 130% of your threat for the mob to attack him (and he should Soulshatter).
So real quickly, what have we learned?
- Damage puts out more threat than healing (So hit 'em hard and hit 'em fast and they won't kill the guy keeping you alive.)
- Global threat is divided evenly between in-combat targets, wheras direct threat is not. (So, again, do a lot of damage--which is always direct threat--and know what generates the most threat.)
- Threat modifiers change the game entirely. (You might be doing half the damage of that Frostfire Mage, but you're doing at least double threat, and with talents he's generating only 60% of his damage as threat.)
- If within melee range, other people need to pass 110% of your threat to get aggro. Ranged allies need to pass 130% (Keep the mobs far away from your ranged friends, and if Bloodlust/Heroism gives them a huge boost in damage, don't worry too much.)
So now we've answered the first three of our four questions, which leaves "How can I improve my threat?". I've got a few answers for that one, because it's a multi-layered issue.
- Tank with the right "buffs"--be it the proper stance (Frost Presence/Defensive Stance), form (Bear), or with the right abilities up (Righteous Fury)
- Stack +Hit (gem for it, enchant for it, and gear for it)
- Stack +Expertise (gem, enchant, gear)
- Know the abilities that put out huge amounts of threat.
From a warrior perspective, don't Devastate if Shield Slam or Revenge are on cooldown, for example.
>>>Some things, though (such as Titanium Weapon Chain and Sorthalis, Hammer of the Watchers) are things you want regardless (The weapon being BiS until you pass Ulduar-25 hardmodes, and TWC being my enchant of choice)
Now, I'm going to go into the relevant stats more--that is, Hit and Expertise. What do they do?
Hit is related to, well, how often you hit something. In Wrath of the Lich King, you need 8% hit (or 263 hit rating) to hit a raid boss 100% of the time with an attack. You will never get a "Miss", just dodges and parries. Most importantly, all of your "yellow" attacks (abilities that use rage/mana/runes/runic power, that make yellow damage numbers instead of white, and usually generate extra threat) will land. A missed 3k shield slam means about 7.5k missed threat.
Now, you might've noticed that I said your attacks might STILL be parried or dodged. That's where expertise comes in. Every point of expertise (aka every 8.2 points of expertise rating) reduces the enemy chance to Dodge and Parry your attacks by 0.25%. If you have 19 expertise, then that's 4.75% less of the time that you will be dodged and parried--which means you'll successfully land a blow roughly 9.5% more often!
Why roughly? Because there is a cap on how much an enemy dodges and parries. Raid bosses dodge 6.5% of the time and parry 14% of the time--so yes, you'd hit 9.5% more often.
BUT, if you had 29 expertise, then you'd reduce their chances by 7.25% each--passing the dodge cap (reduced to 0, not -0.75) so you'd hit 13.75% more often.
Therefore: Good threat requires use of proper tanking abilities and good gear. This isn't to say that you cannot generate threat without high +hit and +expertise. You definitely can (but not missing on your attacks does help a lot).
BUT HOW DO I KNOW WHAT MY THREAT IS, AS WE SPEAK?
Well, Blizzard has a built-in threat meter, but in my opinion it's fairly low quality.
Omen is a threat mod with the following features:
- Omen tracks everything threat related from fight to fight. This means not just your threat on the mob you're fighting. It means everyone's threat on every mob in the current fight, so you can target switch without worrying.
- It tracks what percent of your threat people are at (If you're offtanking at 93k threat and a dps is at 78k and the main tank is at 117k, next to their names it will say "DPS X: 83%" and "MAIN TANK Y: 126%), so you can tell if DPS are passing the 110/130 threshold.
- It tells you what your (and other people's) Threat Per Second is (In a 10man environment I'd say I'm around 5.5k, with vigilance on a high dps it's more like 6.5k+)
Thanks for reading my Threat Guide
PS: For further reading, I recommend the following guides on Tankspot.com:
Death Knight Threat Values A quick look at the threat modifiers for Death Knight abilities.
Paladin Threat Values A swift glance at the threat modifiers on Paladin moves.
Warrior Threat Values An expedient examination of the threat modifiers on Warrior techniques.
There is no Druid threat value list on Tankspot :(
Gearing For Threat A handy guide (more warrior-oriented, but valuble for all classes) that covers Hit/Expertise as well as Strength and Shield Block Value.