Armor

Armor is an attribute shared by all units. Armor is used to determine the amount of damage reduction (or amplification if an armor value is negative) a unit takes from physical damage sources. Higher armor values reduce more damage. Armor is increased by Agility, certain abilities, and some items. Most items in the armor shop will provide armor bonuses.

Armor and effective HP
It is useful to first understand the concept of effective HP. The amount of physical damage a unit can take before dying (hence likelihood of surviving) is not proportional to damage reduction percentages, but to effective HP. Effective HP is the amount of physical damage one can take before dying, and is based on the unit's HP.

For positive armor values, a unit gains 6% of their health per armor as effective HP. A hero with 0 armor and a base HP of 1000 will increase his effective HP by 60% if he increases his armor to 10.


 * 0 → 10 armor: 1000 → 1600 effective HP.


 * 0 → 20 armor: 1000 → 2200 effective HP.

One has to consider that effective HP only takes physical damage in consideration. The example assumes that all the damage the unit takes is physical. Armor actually grants 6% of the physical damage one takes. This becomes more evident with burst magical damage (such as Lina's or Lion's ultimate): the armor value in those cases count for nothing.

For negative armor values, the effective HP reduction diminishes with decreasing armor, trending towards 50%.

Calculating effective HP
For positive armor values:


 * Effective HP = Total HP (1 + Armor points  0.06)

Example:


 * A level 25 has a total HP of 2183 and 11.46 points of armor. What is his effective HP vs physical damage?


 * 2183 HP (1 + 11.46  0.06) = 2183 HP  1.6876 = 3684 effective HP


 * Sven can tank 3684 of physical damage before he dies.

For negative armor values:


 * Effective HP = Total HP (1 - 0.06  Armor points) / (1 - 0.12  Armor points)

Example:


 * The same Sven from previous example is hit by a maxed . His armor is now -8.54. What is his effective HP vs physical damage?


 * 2183 (1 - 0.06  -8.54) / (1 - 0.12  -8.54) = 2183 HP  1.51  2.02 =  1631 effective HP


 * Sven can tank 1631 of physical damage before he dies.

Damage reduction/increase
The damage reduction and increase percentage formulas are directly related to the effective HP formulas in the previous section, and can be derived through algebra. All units, including buildings, have an inherent base armor value and armor type. Any physical damage dealt to a unit will suffer either damage reduction or a damage increase depending on the target's armor.


 * Damage reduction = (0.06 armor)  (1 + 0.06  armor)

Units with negative armor values increase any physical damage they receive.


 * Damage increase = (0.06 |armor|)  (1 + 0.06  |armor|)

Or, the damage multiplier for both positive and negative armor:


 * Damage multiplier  = 1 - 0.06 armor  (1 + 0.06  |armor|)

In Dota 2, the cap on this number is 100% damage amp, but it requires an infinite amount of negative armor to truly reach this cap.

This is different from WC3 DotA, where armor cannot be reduced below &minus;20. Also, a more aggressive damage amplify formula is used resulting in a max damage increase of 71 %. See Negative armor disparity for more information.

Table of damage multipliers at different armor values

 * {| class="wikitable" width = "480px"

! class = "header" width = "10%" align="center" | Armor ! class = "header" width = "40%" align="center" | Damage multiplier ! class = "header" width = "10%" align="center" | Armor ! class = "header" width = "40%" align="center" | Damage multiplier
 * align="center" | -20
 * align="right" | 154.5%
 * align="center" | 1
 * align="right" | 94.3%
 * align="center" | -19
 * align="right" | 153.3%
 * align="center" | 2
 * align="right" | 89.3%
 * align="center" | -18
 * align="right" | 151.9%
 * align="center" | 3
 * align="right" | 84.7%
 * align="center" | -17
 * align="right" | 150.5%
 * align="center" | 4
 * align="right" | 80.6%
 * align="center" | -16
 * align="right" | 149.0%
 * align="center" | 5
 * align="right" | 76.9%
 * align="center" | -15
 * align="right" | 147.4%
 * align="center" | 6
 * align="right" | 73.5%
 * align="center" | -14
 * align="right" | 145.7%
 * align="center" | 7
 * align="right" | 70.4%
 * align="center" | -13
 * align="right" | 143.8%
 * align="center" | 8
 * align="right" | 67.6%
 * align="center" | -12
 * align="right" | 141.9%
 * align="center" | 9
 * align="right" | 64.9%
 * align="center" | -11
 * align="right" | 139.8%
 * align="center" | 10
 * align="right" | 62.5%
 * align="center" | -10
 * align="right" | 137.5%
 * align="center" | 11
 * align="right" | 60.2%
 * align="center" | -9
 * align="right" | 135.1%
 * align="center" | 12
 * align="right" | 58.1%
 * align="center" | -8
 * align="right" | 132.4%
 * align="center" | 13
 * align="right" | 56.2%
 * align="center" | -7
 * align="right" | 129.6%
 * align="center" | 14
 * align="right" | 54.3%
 * align="center" | -6
 * align="right" | 126.5%
 * align="center" | 15
 * align="right" | 52.6%
 * align="center" | -5
 * align="right" | 123.1%
 * align="center" | 16
 * align="right" | 51.0%
 * align="center" | -4
 * align="right" | 119.4%
 * align="center" | 17
 * align="right" | 49.5%
 * align="center" | -3
 * align="right" | 115.3%
 * align="center" | 18
 * align="right" | 48.1%
 * align="center" | -2
 * align="right" | 110.7%
 * align="center" | 19
 * align="right" | 46.7%
 * align="center" | -1
 * align="right" | 105.7%
 * align="center" | 20
 * align="right" | 45.5%
 * }
 * align="center" | -4
 * align="right" | 119.4%
 * align="center" | 17
 * align="right" | 49.5%
 * align="center" | -3
 * align="right" | 115.3%
 * align="center" | 18
 * align="right" | 48.1%
 * align="center" | -2
 * align="right" | 110.7%
 * align="center" | 19
 * align="right" | 46.7%
 * align="center" | -1
 * align="right" | 105.7%
 * align="center" | 20
 * align="right" | 45.5%
 * }
 * align="center" | 20
 * align="right" | 45.5%
 * }

Negative armor disparity
Amplified damage from negative armor is calculated differently in WC3 DotA than in Dota 2. In DotA the amplified damage is calculated from this formula:


 * Damage increase = 1 - 0.94^(-armor)

Negative armor in DotA has a cap of -20 armor (71% damage increase). Further reducing the armor will not change the damage increase.

Unit armor
Unit armor refers to the four basic armor types of most non-Hero units. Light armor is the default armor type of units. Unarmored and light units take 100% damage from all sources except piercing damage, which deals 200% to light armor and 150% to unarmored units. Medium armor takes reduced damage from piercing and siege damage, but increased normal damage. Heavy armor takes reduced damage from piercing damage, but increased damage from siege and normal damage.

(Actually, Heavy armor has no resistance benefits but it takes more damage from magical attacks. It is only called as Heavy Armor since most units have this armor property has high Armor values.)

Fortified armor
Fortified armor is the type used by buildings and some other units. It takes reduced damage from most sources and is one of the sturdiest types of armor, but takes increased damage from siege. Fortified armor has an innate 50% damage resistance to Heroes.

Hero armor
Hero armor is used by all Heroes in Dota 2. It provides increased resistance to most damage types, except other Heroes and Chaos. Hero armor has an innate 25% magic resistance with the exception of Visage, whose magic resist starts at 10% and is increased by levels in Gravekeeper's Cloak, and Meepo, with a base of 35%. This is calculated separately from armor.

Table of resistances
Corrections: 1) Normal Damage deals 100% damage to all types of armors except: They Deal more Damage in Medium Armored units and Deal less damage to Fortified armor units. 2) Siege Damage deals extra damage to Unarmored units and Fortified units but deals less damage to Medium armored units. 3) Chaos Damage deals 100% damage to all Armor types, but deals more damage to Fortified units, not less damage to Fortified units. 4) Hero damage deals more damage to Unarmored units since the Unarmored units is property says "Unarmored units takes extra damage from Siege and Hero attacks. 5) Magic attacks deals less damage to, Light, Medium, Hero and Fortified units but deals more damage to Heavy Armored units.

Armor and Damage block

 * Actual damage = (Damage from attacker - ¹Damage block) * (1 - ²physical resistance) * (³Armor type %)

¹Only when damage block occurs. ²Based on armor value and its formula to yield resistance. ³According to 'Table of resistances' above.