Melee Combat Mechanics
 

[b]This article has not been updated for 3.0.[b]
Crushing blow mechanics have been modified so that +3 creatures and bosses will no longer crush players. The rating conversions are also different at level 80. This article will be updated as the author has time to do so. Please do not post comments pointing out inaccuracies introduced by the 3.0 patch until such time.


This article discusses the underlying mechanics that happen when melee attacks are made.

 

Contents

1Possible Outcomes 1.1Facing 1.2Armor Class-based Damage Reduction 1.3Parry & Attack Speed Reduction 1.4Glancing Blow / Crushing Blow Rate 2Player vs. Environment 2.1White vs. Yellow attacks 2.2Hit Table 2.3Examples 2.4One roll vs Two roll 3Environment vs Player 3.1Hit Table 3.2Critical Hit Immunity 3.3Crushing Blows 3.4Examples

[top]Possible Outcomes

When a melee attack is made, one of several results will occur. The chance of each of these factors depends on a large number of variables, most of which are described on the Stat Conversion page.

• Hit: The attack hits normally.
• Critical Hit: The attack hits for double damage.
• Miss: The attack doesn't land. Dual wielding adds 19% miss chance to white attacks, but not to yellow.
• Dodge: The target of the attack dodges.
• Parry: The target of the attack parries.
• Block: The target blocks some or all of the damage of the attack.
• Crushing Blow: The target is hit for 150% of normal damage. This is an NPC-only mechanic.
• Glancing Blow: The attack hits for 76% of normal damage. This is an NPC-only mechanic.

The chance of any one of these occurring is determined every time an attack happens. The outcomes are prioritized and when the individual chances are summed to 100%, a single roll is made against that sum. The sum of all the chances is called the Hit Table. The hit table works differently when players attack NPCs than when NPCs attack players. Both variations are explained below.

[top]Facing

A note on facing: parries and blocks only occur when the attack is made in the target's frontal 180 degrees of facing. Thus is is always better to attack from the rear when possible.

It is possible for attacks that are only allowed from the rear (such as Backstab) to be parried or blocked -- this can occur when a boss' facing changes server-side but this change is not reflected on the client side in time to prevent the attack from occurring. This can also affect the player's ability to block NPCs, which has ramifications regarding Crushing Blows (discussed below).

It is likewise possible for a player to be considered both in front of an behind a target due to slight positional differences between the client and the server.

[top]Armor Class-based Damage Reduction

All players and NPCs have some amount of armor class that reduces incoming physical damage. This amount does not vary from attack to attack; it only changes when the player's gear changes or various debuffs are applied. This damage reduction amount is hard capped at 75%.

A player may calculate their reduction at level 70 against another level 70 target (i.e. the tooltip AC value) using the following formula:


This can be simplified as:


Defending against a level 73 NPC, the constant changes because of the NPC's level and the formula is:


Damage reduction from armor class is very straightforward: it reduces the damage of the attack by the specified amount. For example, an attack that does 100 damage against a player with 25% damage reduction will do 75 damage. A player with 60% damage reduction will reduce a 20,000 damage hit to 8000.

[top]Parry & Attack Speed Reduction

When you parry an attack, it reduces the time of your next main hand attack. This applies to both players and NPCs, so when an NPC parries an attack its next attack may occur more quickly than normal. Depending on how much time is left until your next attack, one of three things will happen to your main hand swing timer:

• If the next attack would normally occur within 20% of your weapon speed after the parry, there is no effect.
• If the next attack would normally occur between 20% and 60% of your weapon speed later, it happens 20% of your weapon speed later instead.
• If the next attack would normally occur more than 60% of your weapon speed later, the time until your next attack is reduced by 40% of your weapon speed.

For example, with a 2.0 speed weapon, if your next attack would normally occur .3 seconds after the parry, it will still happen at that time. If it would normally occur anywhere between .4 and 1.2 seconds after the parry, it instead happens .4 seconds later. And if it were to normally happen 1.5 seconds after the parry, this would be reduced by .8 seconds causing it to happen .7 seconds later.

This can be reproduced by plotting the time between attacks after parrying against the expected time remaining on your swing as seen in this thread.

[top]Glancing Blow / Crushing Blow Rate

In a situation where the player has maxed weapon skill and defense and the NPC does not have higher-than-normal defense or weapon skill, the rate at which Crushing Blows and Glancing Blows occur is 10% per level above the player, minus 15%. This means that a NPC that is 2 levels higher has a 5% chance to cause the player to glance or to hit them with a crushing blow, a NPC 3 levels higher has a 15% chance, a NPC 4 levels higher has a 25% chance, and so on.

There are a few NPCs that have higher-than-normal Defense that will cause the player to glance at a higher-than-expected rate for their level, but they are very rare. Notably, many NPCs in Silithus had higher defense for their level than what is normal.

[top]Player vs. Environment

This section is in regards to attacks made by players against NPCs (DPS). Attacks made by players against NPCs will scale downwards exponentially as the level of the NPC increases above the player. This means that an NPC that is four levels higher than the player is drastically more difficult to hit than an NPC three levels above the player, and this continues as the NPC's level increases. Since Boss mobs are three levels above the player, it is important to understand that even by this point there are already sharp decreases in player damage against such NPCs.

[top]White vs. Yellow attacks

All auto-attack hits are resolved as normal hits and show up as "white" damage in the scrolling combat text. Special attacks show up as "yellow" and differ from white attacks in the following manner:

• Yellow attacks are not subject to glancing blows.
• Some yellow attacks are determined by a two-roll system. This primarily affects Rogues.
• Yellow attacks will not generate rage for a Warrior.
• Instant yellow attacks such as Mortal Strike or Backstab are no longer eligible to generate extra strikes from the effect of Windfury Totem. The exceptions are on-next-swing abilities where your normal melee strike is replaced by a special attack, such as Heroic Strike or Cleave.

[top]Hit Table

The hit table when players attack NPCs is different than the attack table used when NPCs attack players. The hit table is the compilation of all outcomes of a given attack after all modifiers have been applied. The range of the hit table is always 100% -- anything that would be "after" 100% is pushed off the table entirely. The order of priority is:

Miss ->Dodge -> Parry -> Glancing Blow -> Critical Hit -> Hit [always fills the rest of the table]

It is possible for one or more of these factors to not apply; for example, equal level or lower mobs have a 0% glancing blow rate. A sufficient amount of +hit (which is more accurately -miss) can remove the miss portion of the table entirely.

Against higher level mobs, players have an increased chance to miss or have their attack dodged or parried. The rate at which this scaling occurs is non-linear in favor of the NPC, and any NPC more than 3 levels above the player becomes a tough target.

Any attack may be blocked by an NPC regardless of whether or not it is a critical hit and thus is it not included on this hit table. After it is determined that the player's attack lands, a seperate block check is made. This is very different than when NPCs attack players and can be a subject of confusion if misunderstood.

It is possible for a player to have a high enough critical chance to remove all normal attacks from the hit table. This is sometimes referred to as the "crit cap". Prior to patch 2.1, the glancing blow rate was high enough against boss mobs (40%) that this was a possible outcome for a player. The glancing blow rate was relaxed in 2.1 to 25% and crit capping is now extremely difficult if not impossible to achieve.

[top]Examples

A Warrior with 25% chance to crit and 5% hit attacks a target of equal level from the front. His hit table will be as follows:

Player vs equal-level NPC, autoattack
Miss: 0% (negated by hit talents and gear)
Dodge: 5% (an equal level target has 5% dodge)
Parry: 5% (an equal level target has 5% parry)
Glancing Blow: 0% (an equal level target will not normally cause a player to glance)
Critical Hit: 25% (as displayed by the character sheet)
Hit: 65% (fills the remainder of the hit table)

The same Warrior later attacks a Boss mob from the front. His hit table is now different:

Player vs Boss, autoattack
Miss: 4% (9% hit is required to never miss against bosses, so the warrior still has a 4% chance to miss)
Dodge: 6%* (Higher-level NPCs have a higher-than-normal chance to dodge)
Parry: 12%* (Higher-level NPCs have a higher-than-normal chance to parry)
Glancing Blow: 25% (standard glancing rate for boss NPCs)
Critical Hit: 24.4% (character sheet crit rate, modified downward by the NPC's improved Defense rating)
Hit: 28.6% (fills the rest of the hit table)

If the player attacked using Mortal Strike or another attack that dealt yellow damage, the Glancing Blows portion of the table would be removed and replaced by another 25% of normal hits.

Player vs Boss, Mortal Strike
Miss: 4%
Dodge: 6%*
Parry: 12%*
Glancing Blow: 0% (Yellow damage never glances)
Critical Hit: 24.4%
Hit: 56.6% (fills the rest of the hit table)

*Note: Boss dodge and parry values are approximate based on parsing. The reason for the higher parry chance that seemingly disobeys normal defense/weapon skill rules is unknown.

[top]One roll vs Two roll

The majority of melee attacks made in WoW use a one-roll system. This means that a single check is made against the hit table to determine the outcome of an attack.

Some special attacks (notably all Rogue special attacks) use a two-roll system. The first roll first checks to see if the attack lands, misses or is avoided. If the attack lands, the second roll checks to see if it hits or crits. Two-roll attacks are observed to be similar to one-roll attacks in all other manners.

This can be proven by using an ability with a very high crit rate against a target that has an ability that decreases the player's ability to hit. For example, Attumen's Intangible Presence debuff decreases the player's chance to hit by 50%. If Backstab had a 60% chance to crit and used the one-roll system, all hits while under the effect of Intangible Presence would be critical hits (since crits override normal hits in the hit table). This is not the case, so it can be deduced that the crit chance is rolled separately from the avoidance check.

[top]Environment vs Player

This section is in regards to attacks made by NPCs against players (tanking). Attacks made against a player by NPCs scale linearly as the level difference between the player and NPC increases or decreases. A player with sufficiently high levels of defensive skills can theoretically survive against an NPC much higher level than them, but in practice players will be tanking mobs no higher than three levels above them once they hit the level cap.

[top]Hit Table

The hit table when NPCs attack players is different than the attack table used when players attack NPCs. The hit table is the compilation of all outcomes of a given attack after all modifiers have been applied. The range of the hit table is always 100% after modifiers -- anything that would be "after" 100% is pushed off the table entirely. The order of priority is:

Miss ->Dodge -> Parry -> Block -> Critical Hit -> Crushing Blow -> Hit [fills the rest of the table]

It is possible for one or more of these factors to not apply. A sufficient amount of Defense can remove the Critical Hit portion of the table entirely, for example.

[top]Critical Hit Immunity

140 extra defense (336 defense rating at 70) over the player's maximum natural defense skill can remove critical hits from this table entirely against Boss NPCs. Druids require 415 defense [156 defense rating] with 3 points in Survival of the Fittest.
It is possible to mix and match Defense and Resilience to achieve critical hit immunity. Each 39.4 Resilience rating (1% reduction) reduces the amount of Defense Rating required by 144. It is important to note that while the Defense requirements are much higher than the Resilience requirements, that amount of Defense also grants the player 2.4% each of Dodge, Block and Parry and decreases the NPC's chance to hit you by this amount, so Defense remains a better overall choice for Warriors and Paladins. Feral tanks cannot parry or block so stacking Resilience is usually an easier route to reaching critical hit immunity for Druids.

[top]Crushing Blows

Bosses have a 15% chance to land a Crushing Blow against a player. It is possible for Warriors and Paladins to push Crushing Blows off of the hit table entirely. For this to happen, a player must fill the entire hit table with nothing but dodge, parry, block, and the NPC's miss chance. This means that the only possible outcomes for an attack by a boss are to miss, be dodged, be parried, or be blocked and thus Crushing Blows cannot occur.

This means that a Warrior with Shield Block active (75% increased block chance) needs to fill 25% of the hit table with other sources of avoidance. Since boss level mobs also have a 0.6% reduced chance to miss, dodge, parry or block due to the +3 level difference, a warrior needs 27.4% avoidance from all sources combined with an active Shield Block in order to become uncrushable. Passive crush immunity is very difficult to attain for a Warrior.

Similarly, a Paladin with Holy Shield active (30% increased block chance) needs to fill 70% of the hit table with other sources of avoidance. Once again allowing for the level difference, a Paladin needs 72.4% avoidance from all sources combined in order to become uncrushable. This can be reduced to 67.1% if the paladin has the [Libram of Repentance] Heroic badge reward, since this increases the effect of Holy Shield by a further 42 block chance rating (5.32%). It is easy for a Paladin to be crush immune for a much higher percentage of time than a warrior since Holy Shield has so many charges. Even if Holy Shield's charges are expended, odds are high that Redoubt will be up which will leave only a very low chance of a crushing blow.

Druids cannot remove crushing blows from their hit table unless they become completely unhittable which is impossible for all practical purposes.

[top]Examples

A warrior with no bonuses to defense is struck by an equal level NPC. The hit table against the player will be as follows:

Even-level NPC vs Player
Miss: 5%
Dodge: 5%
Parry: 5%
Block: 5%
Crushing Blow: 0%
Critical Hit: 5%
Hit: 75%

This warrior is not a very good tank. Let's give him some gear that improves his defense skill to 490, which improves his Dodge, Parry, Block and chance the NPC will miss him by 5.6% each and removes any chance he will be critically hit:

Even-level NPC vs Player
Miss: 10.6%
Dodge: 10.6%
Parry: 10.6%
Block: 10.6%
Crushing Blow: 0%
Critical Hit: 0%
Hit: 57.6%

This warrior is a much better tank now! Let us see how he fares against a Boss NPC:

Boss vs Player
Miss: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Dodge: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Parry: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Block: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Crushing Blow: 15%
Critical Hit: 0%
Hit: 45%

The Boss NPC has a higher weapon skill that negates a part of the Warrior's improved Defense rating, but the warrior still has enough defense to avoid critical hits. He doesn't fill the hit table enough to push Crushing Blows off though, so the Boss still might send him to the spirit healer with an unlucky string of Crushes.

If the Warrior uses Shield Block (75% extra Block Chance), the hit table becomes:

Boss vs Player, active Shield Block
Miss: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Dodge: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Parry: 10% (Character sheet shows 10.6%, but this is reduced by .6% due to level difference)
Block: 70% (The player has 85.6% block in this situation [reduced to 85% block by level difference], but only 70% is needed to fill the hit table)
Crushing Blow: 0%
Critical Hit: 0%
Hit: 0%

The huge improvement in Block Chance leaves no room on the hit table for Crushing Blows nor normal hits (nor Critical Hits if the Warrior is not normally crit immune) and the Warrior is much tougher to kill as a result.