Armour

For equipment classified as armour, see Armour (equipment).

For the basic passive skill, see Armour (passive skill).

Armour is a form of defence that reduces incoming physical damage from hits. Along with Evasion and Energy shield, Armour is one of the three defence types that can implicitly appear on equipment. Unlike resistance, Armour reduces damage by up to a constant value, rather than a proportion of the total damage: every 10 points of Armour blocks up to 1 physical damage per hit. The absolute amount of damage reduced gets closer to the maximum the more damage the hit does.

Armour rating can be increased by wearing equipment, taking certain passive skills, using spells such as , and drinking a Granite FlaskGranite FlaskLasts 6.00 Seconds
Consumes 30 of 60 Charges on use
+1500 to ArmourRequires Level 27Right click to drink. Can only hold charges while in belt. Refills as you kill monsters..

Supposedly the most armour monsters have in the game is about 983.

Mechanics

Damage reduction from armour only reduces physical damage taken from hits. Elemental damage and damage-over-time are not affected.

The amount of damage reduction is a function of armour rating and the damage taken. Damage reduction is capped at 90%.

Damage Reduction Factor = Armour / ( Armour + (10 * Damage) )

For example, if you have 1200 armour rating this chart indicates how much damage will be reduced by:

File:Damage reduction chart.png The vertical axis is damage reduction percent. The bottom axis is original damage.

Equivalently:

Net Damage = Raw Damage2 / (Raw Damage + Armour / 12)
Defense Factor = Raw Damage / Net Damage = 1 + Armour / (12 * Raw Damage) 
= (1 + sqrt(1 + Armour / (Net Damage * 3))) / 2

Therefore we can conclude:

• If raw damage is much less than Armour / 12, raw damage has a near-quadratic effect on net damage. Equivalently, in this regime raw damage has a near-linear effect on net DPS if the raw DPS is held constant.
• If raw damage is much greater than Armour / 12, raw damage has a near-linear effect on net damage. Equivalently, in this regime raw damage has little effect on net DPS if the raw DPS is held constant.
• Against attacks of a fixed raw damage, armour has a linear effect on the number of attacks it takes to deplete a certain amount of hit points.

Another way of looking at it is in terms of absolute damage reduction:

Absolute damage reduction = Armour / 12 * Raw Damage / (Raw Damage + Armour / 12)

So damage from attacks is reduced by up to 1 per 12 points of Armour, which means that the supposed monster Armour cap of 983 blocks up to 77.5 damage per attack. Note that as raw damage increases, the damage blocked per attack increases, but the proportion of damage blocked decreases.

The derivative of this with respect to Armour is

dAbsolute damage reduction/dArmour = ((Armour / 12) / (Raw Damage + Armour / 12))2

Skills

The aura increases armour of the character and nearby allies. The and skills temporarily grants player additional armour.

Passive skills

There are passive skills that grant armour bonuses.

Armour rating

These passive skills grant increased armour rating or additional base armour rating. The Iron Reflexes keystone is special in that it converts evasion rating to armour rating.

Armour rating on shields

These passive skills grant increased armour rating from equipped shields.

Miscellany

These passive skills are related to armour, but do not fit into any other category.