Threat is a measure of an NPC's aggression towards a player. Each NPC has a threat table, and the character at the top of the list is usually the target of its aggression. In-game, this is known as having aggro from that particular NPC. The NPC will attack that character if possible, unless another character manages to change the NPC's target.
Threat does not determine whether or not a mob will attack, only what it will attack if it does. A player's threat value cannot drop below 0, and reaching 0 threat does not remove a player from combat with the mob.
Damage is the most basic form of threat generation. Threat measurements are normalized so that 1 point of damage generates 1 point of threat. Many abilities generate additional threat that is not tied to their effect (damage dealt, buffs, debuffs). The bonus threat values are listed below.
Threat caused by beneficial effects is divided amongst all NPCs that are aware of the character. This global threat applies to heals, bonus threat from buffs (such as or ), and power gains (such as a or ).
Healing threat is global, and is normally 0.5x of the amount healed; hence, healing effects cause no threat if the target is already at full health. For example, say Player 1 is involved in combat with 5 mobs, and Player 2 heals Player 1 for 1000 health with no threat reduction talents. A 1000 heal generates 500 threat; however, that 500 threat is split among the 5 mobs. Therefore, Each of the 5 mobs now has 100 threat towards Player 2.
If a power gain (rage/mana increase) shows up in the combat log, the effect usually counts as a buff with bonus threat attached to the event. There are no energy-increasing effects that appear to cause bonus threat. Normal power or health regeneration does not generate threat.
In general, NPC attacks on a player do not affect threat (you don't gain/lose threat by being attacked). However, some NPCs have special moves that affect threat.
Threat tables per class
Threat auras affect the threat value of all abilities under their jurisdiction of effect that are used while the threat-modifying aura is active (which is always, in the case of passive modifications). Threat-modifying abilities have a direct effect on the threat level of one or more characters. Note that static values added to the threat an ability generates are added before threat auras are applied, and thus are increased or decreased by any threat auras that may be active when the ability is used. The static values listed in the chart below are the base values before threat auras.
An increase in threat by X% is equal to multiplying the current modifier (which begins at 1.0) by (1 + X%/100); for example, a threat increase of 20% would be a multiplier of 1.20. Likewise, a decrease in threat by X% is a multiplier of (1 - X%/100); a threat decrease of 30% would be a multiplier of 0.70.
Threat modifiers stack multiplicatively when calculating the threat for an ability affected by more than one modifier. The final threat modifier for an ability is determined by multiplying all the active modifiers together; if the previous two examples were active simultaneously, the total threat caused would be 1.00 (baseline) * 1.20 * 0.70 = 0.84, or 84% of the threat that you would have caused without multipliers.
NOTE: The threat system was heavily overhauled again for Cataclysm and Mists of Pandaria. The numbers in these tables have been updated to the extent of understanding that community research has achieved so far. Also, be aware that many ability pages have not been properly updated for the post-MOP values and may contradict the values in this table.
Stacked threat auras
Threat auras stack in a multiplicative fashion. A common but wrong assumption is that due to this mechanic, threat reduction effects provide less benefit the more a player has; in fact, threat reduction is always equally powerful, no matter how much a player has.
Example: You are a Priest casting a Binding Heal. Threat is normally 0.5x healing done, and Binding Heal has an additional 0.5 modifier built in:
Your healing threat would be: 0.5 * 0.5 = 0.25x healing done.
Threat modifying items
|-640 Threat ~ 30 Yards, 5min cooldown|
|-720 ~ 30 Yards, 5min cooldown|
|-1075 ~ 30 Yards, 5min cooldown|
|Reduces threat from your harmful critical strikes|
|-901 ~ 30 Yards, 2min cooldown|
|Back||Reduce threat slightly and increase Spirit by 10.||Enchanting (440)|
|Hands||Increase threat caused by 2% and increase parry rating by 10.||Enchanting (435)|
|Back||Decrease threat from all attacks and spells by 2%.||Enchanting (300)|
|Hands||Increase threat from all attacks and spells by 2%.||Enchanting (300)|
|-1500 ~ 30 Yards|
|Meta||2% reduced threat||+54 Intellect|
|Meta||2% reduced threat||+21 Intellect|
|Meta||2% reduced threat||+12 Intellect|
- Being noticed by an aggressive NPC does not generate any threat. This behavior places that character on the NPC's threat list, but with a threat value of 0.
- Threat doesn't decay (passively degenerate over time) unless a specific encounter is designed that way. The exception to this rule is threat generation by abilities such as or . Threat generated from these abilities disappears after 30 seconds.
- A character's threat level is reset if the character leaves combat with the mob (dies, moves far enough away).
- A character's threat level cannot be negative.