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- This article is about the class ability for blocking damage. For the combat skill, see block rating. For preventing another player from contacting you, see Ignore.
Block is the ability of a shield to absorb melee damage in addition to its armor value. When a shield is equipped, you have a certain chance to perform a block, the amount of damage of which is influenced by block value. The basic chance to block an attack is indicated on your character sheet under the Defense tab. This value assumes that you fight against a mob or other character of same level. Fighting a mob of higher level than yourself decreases your chance to block, and vice versa.
The fact that a Block may only mitigate damage partly—which means the enemy's attack speed and damage per attack becomes a factor—and the fact that the talents increasing Block chance cannot reliably be active at all times, makes it harder to calculate the actual benefit of Block in comparison to other damage mitigation mechanics, such as armor or chance to get missed.
While it is clear that a Blocked attack made against a player cannot be a crit, it is possible that mobs have different rules for determining whether an incoming attack is blocked or not, which includes the possibility of a "blocked crit".
It should be noted, however, that only special attacks—i.e. yellow-damage instant attacks such as Claw, Overpower, and Sinister Strike, and yellow-damage on-next-swing attacks such as Heroic Strike and Raptor Strike—have been observed as inflicting blocked crits. Normal white-damage auto-attacks have never been seen inflicting a blocked crit, and are probably subject to the same mutually-exclusive-attack-result rules that attacks made against players are.
Note too, that unlike player characters, mobs sometimes block attacks even though they have no shield equipped.
Chance to block Edit
Your base chance to block an attack is 5% and this is modified by a factor of the rating difference between the attacker's weapon skill and the defender's defense and block rating. Each point of difference adjusts the base chance by 0.1% if the target is a mob and 0.04% if the target is a player. Mobs level 9 and lower do not block as frequently, just as they are not missed as frequently as they should be. Also, mobs cannot block more than 5% of attacks regardless of rating difference.
The formula: Block% = 5% base chance + contribution from Block Rating + contribution from talents + ((Defense skill - attacker's weapon skill) * 0.04)
In combat, you will notice that the percentage of incoming attacks that are Blocked matches the Block percentage shown in your tooltips. Miss chance and Critical chance are unmodified by your Block chance, so you're not "wasting" Blocks on misses nor are you able to Block a Critical. This may seem odd to some folks if they are expecting a "if hit, then check if Parry, then check if Block, then check..." type system. WoW, like many other games, uses a combat results table-based combat scheme (where one roll determines outcome of an attack), so percentages are absolute.
Your parsed Block percentage won't necessarily match your tooltip if you're fighting creatures higher or lower in level to you. See the Defense formula above to understand.
Damage reduction Edit
The amount of damage a Block reduces depends on the block value of your shield, any enchantments, talents and your Strength. Damage reduced by blocking is calculated after other damage reducing factors, such as armor, which increases the effectiveness of blocking.
Block value modifiers Edit
Block value modifiers that increase block value by a percentage are added together as modifiers before being applied to the character's base block value.
For example, a Warrior's Shield Block skill increases block chance and value by 100%, and most tanking Warriors will also have the Shield Mastery talent (+30% block value). This is calculated in the following fashion:
The modifier is 2.3 (230%) because the bonuses from Shield Block (100%) have been added to Shield Mastery (30%) before being applied to the base block value (100%). Temporary block value from librams, trinkets, or other items is included in the original base block value calculation, and therefore benefits from all block value modifiers.
The quantity of damage blocked is calculated after damage mitigation from all other sources (Armor, Defensive Stance, Improved Righteous Fury, Blessing of Sanctuary, etc.). That means if the opponent hits you for 200, mitigated to 100 by Armor, and block according to the formula above is 40, then you will see in your combat window: "... hits you for 60. (40 blocked)".
If the block quantity is greater than the damage received after mitigation, you will then block 100% of the damage: "... attacks. You block."
Changes for CataclysmEditThis section concerns content exclusive to Cataclysm.
As of Cataclysm the mechanics behind block will be changed dramatically. Instead of blocking a flat amount of damage you will then always block 30% of the damage, with block rating still defining how often you will block. This means that the Block Value stat will be gone, though the 30% will likely become subject of talents and/or glyphs, one known block modifier in Cataclysm will be the Protection Warrior's Mastery bonus: Critical Block which has a chance to block twice as much incoming damage.
- Patch 1.3.0 (07-Mar-2005):
- All creatures will now report a Block on attacks from the front, reducing damage caused instead of converting the attack into a "Miss." Creatures will no longer be able to Block attacks from behind.
- Blocking an ability that takes place on the next swing now blocks the normal amount of damage instead of all of it.