Attack Damage

Attack damage is the amount of damage a unit is dealing with an unmodified basic attack; the base values are different for every hero. The total attack damage of a unit is the sum of main attack damage and bonus damage. Attack damage is reduced by armor.

Final attack damage


Formula: 
 * final attack damage =
 * [ (main damage + bonus damage) × critical strike multiplier - blocked damage ]
 * × armor value multiplier × armor type multiplier
 * × Π general damage multipliers



Base attack damage
Base attack damage is the part of the main attack damage that never changes throughout a game. It consists of two values, a minimum and maximum amount. Every time an attack is issued, a random value between these two extremes is chosen. The best example for this is Chaos Knight since his base damage varies between 29 and 59. The difference of 30 is always part of the total attack damage, no matter how many attributes or how much bonus damage is acquired.

Main attack damage
Main attack damage is the damage value shown in white numbers on a hero's statistics consisting of the base damage with the damage granted by a hero's primary attribute on top. The only way to improve a hero's main attack damage is to increase its primary attribute. Attribute points can be increased by acquiring levels, as well as specific skills and items. This also means that the value of items granting attribute points differs depending on whether it is equipped by a strength, agility or intelligence hero.

Formula:
 * main damage = base damage + primary attribute points.

Bonus attack damage
Bonus damage is the damage value shown in green numbers on a unit's statistics. Whenever an item or skill shows a +damage value, it increases the bonus damage of the affected unit.

For example give + bonus damage, while  gives + bonus damage for a unit with 100 main damage. adds negative bonus damage which is equal to a reduction.

Formula
 * bonus damage = sum of bonuses + sum of reductions.

Critical strike multiplier
The highest critical strike increases main and bonus damage by a certain factor.

Blocked damage
Damage Block is a passive ability that gives the wielding unit a chance to block some physical damage from an attack. Only one source of damage block can trigger per attack.

Armor value multiplier
The target's armor influences the attack damage by a factor that asymptotically lies between 0 and 2 and is 1 for a target that has no armor.

Formula
 * armor value multiplier = 1 - 0.06 × armor ÷ (1 + 0.06 × |armor|).

Armor type multiplier
Depending on the combination of the attack damage type and armor types, an armor type multiplier modulates the attack damage.

General damage multipliers
A couple of abilities like and  reduce all incoming damage, including physical attack damage.

Attack damage types
There are several different types of attack damage, which determine how much damage a unit's attack deals against certain armor types. Each of the 4 different attack types deals either reduced, increased, or unchanged damage against each of the armor types, on top of it being also manipulated by the armor value of the target.

Example A hero with 100 attack damage attacking a siege unit which has 0 armor deals 50 damage to it, because the attack type "hero" deals 50% less damage against the armor type "structure", which is the siege creeps' and all buildings' armor type. If the siege creep would gain 5 armor, the 100 damage attack would deal (100 * 0.769 * 0.5) = 38.45 damage. The same attack would deal 76.9 damage to a unit with any other armor type, since attack type hero deals full damage to them.

This table shows how much damage each attack damage type deals against each armor type, and which units use which attack damage type:

Instant attacks
Several abilities make use of the hero's regular attacks. However, these attacks are instant. This means they do not use the hero's attack animation, are independent from attack speed and ignore the regular downtime between attacks. If an instant attack is performed by a ranged hero, it still uses their regular attack projectile for the attack, unless it is set not to. If an instant attack occurs while already attacking an enemy normally, it does not interfere with the regular attack. They do not interfere with any other actions of the hero either, meaning they do not interrupt movement, do not cancel spell casts and do not stop channeling spells of the hero.

Since instant attacks do not use attack animations and jump straight to the attack point, they cannot proc effects which react on the start of an attack, like or. However, they can proc effects which react on attack hit, such as and, although there are some exceptions to this. Instant attacks may proc on-hit effects only when they are allowed to. An instant attack which is not allowed to proc attack modifiers is not allowed to proc on-hit effects either. Just like regular attacks, instant attacks also cause the attacking hero to get revealed if attacking from the Fog of War.

The following abilities make use of instant attacks:

1 These instant attacks may not proc any attack modifiers or on-hit effects.

Conditional bonus
These abilities give direct attack damage bonuses under certain circumstances. Due to this, they do not display their bonus damage in the HUD. Their damage type can also vary and is not necessarily physical; nonetheless, they still count as attack damage since their damage is dealt in one instance together with a unit's attack damage. This means they are affected by armor type, but not by spell damage amplification.