# Armor

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Armor is a stat shared by all units, including minions, monsters, and buildings. Increasing armor reduces the physical damage the unit takes. Each champion begins with some armor which increases with level ( being the only exception). You can gain additional armor from abilities, items, masteries, and runes. Armor stacks additively.

Excluding whose base armor does not scale with levels, base armor ranges from 65.5 () to 104.5 () at level 18.

## Damage reduction

Incoming physical damage is multiplied by a factor based on the unit's armor:

$${\rm Damage\ multiplier}=\begin{cases} {100 \over 100+{\it Armor}}, & {\rm if\ }{\it Armor} \geq 0\\ 2 - {100 \over 100 - {\it Armor}}, & {\rm otherwise} \end{cases}$$

Examples:

• 25 armor → ×0.8 incoming physical damage (20% reduction, +25% effective health).
• 100 armor → ×0.5 incoming physical damage (50% reduction, +100% effective health).
• −25 armor → ×1.20 incoming physical damage (20% increase, −16.67% effective health).

## Stacking armor

Every point of armor requires a unit to take 1% more of its maximum health in physical damage to be killed. This is called effective health.

Example: A unit with 60 armor has 60% more of its maximum health in effective health, so if the unit has 1000 maximum health, it will take 1600 physical damage to kill it.

What this means: by definition, armor does not have diminishing returns in regard of effective hitpoints, because each point increases the unit's effective health against physical damage by 1% of its current actual health whether the unit has 10 armor or 1000 armor.

In terms of effective HP per point of armor, armor does have diminishing returns in a way HP does not. While 1 point of armor gives 1% more effective HP, even with 0 armor you have 100% "for free".

Example: A unit with 1000HP and 100 armor has 2000 effective HP and thus 20 effective HP per armor. If it buys 100 more armor it will have 1000HP, 200 armor, 3000 effective HP and therefore 15 effective HP per armor.

Buying only armor is inefficient compared to buying the optimal balance of HP and armor, it is important to not stack too much armor compared to HP or else the effective HP will not be optimal.

When a unit's armor is negative because of armor reduction or debuffs, armor has increasing returns, because negative armor cannot reduce effective health to less than 50% of actual health. A unit with −100 has 66.67% (gains −33.33%) of its maximum health as effective health.

## Armor as Scaling

These use the champion's armor to increase the magnitude of the ability. It could involve total or bonus armor. By building armor items, you can receive more benefit and power from these abilities.

### Champions

• grants armor equal to 15 / 17.5 / 20 / 22.5 / 25 + (10 / 11.5 / 13 / 14.5 / 16% bonus armor) to himself and the target ally for 3 seconds.
• grants armor to herself equal to 20 / 30 / 40 / 50 / 60 + (20% bonus armor) for 3 seconds, deals damage after that time to units around her, and retains the defensive buff for an additional 3 seconds if any enemy is struck by the blast.
• passively grants armor to himself equal to 10 / 15 / 20 / 25 / 30% of his total armor.
• deals 15 / 30 / 45 / 60 / 75 + (10% armor) + (10% AP) physical splash damage per basic attack in a 225-radius.
• deals 60 / 100 / 140 / 180 / 200 + (30% armor) + (20% AP) magic damage.
• grants attack damage to himself equal to 25% of his total armor.
• increases his armor by 40 / 60 / 80 / 100 / 120 for 6 seconds, and deals 15 / 25 / 35 / 45 / 55 + (10% armor) magic damage to enemies who basic attack him.
• grants his next basic attack bonus magic damage equal to 20% of his total armor after using an ability.
• passively grants 10 / 15 / 20 / 25 / 30 bonus armor to himself and 12% of his total armor to himself and nearby allied champions.
• deals 40 / 80 / 120 / 160 / 200 + (20% armor) magic damage in a 375-radius and reduces nearby enemy armor by 5 / 10 / 15 / 20 / 25 + (5% armor) for 4 seconds.
• steals instantly 20% of the target's armor. He continues to drain an additional 20% the target's armor over 4 second before decaying 4 seconds after the drain completes.

### Items

• , upon being hit by a basic attack, reflects magic damage back to the attacker equal to 25% of your bonus armor plus 15% of the incoming damage (before being reduced by defenses).

## Increasing armor

### Items

• : +40 armor. 800 .
• : +15 armor. 300 .
• : +50 armor, +600 health. Unique Passive – Dreadnought: While moving, build stacks of Momentum, increasing movement speed by up to 60 at 100 stacks. Momentum quickly decays while under any other form of crowd control, and slowly decays while slowed. Unique Passive Crushing Blow: Basic attacks discharge all Momentum, dealing 1 bonus physical damage per 2 stacks. If 100 stacks are discharged, damage is doubled to +100 and the target is slowed by 75% decaying over 1 second (melee only). 2750 .
• : +90 armor, +400 mana. +20% cooldown reduction. Unique Aura: Nearby enemies suffer −15% attack speed. 2600 .
• : +20 armor, +250 mana. Unique Passive: +10% cooldown reduction. 900 .
• : +65 armor, +20% cooldown reduction, +500 mana. Unique Passive – Spellblade: After using an ability, the next basic attack (on hit) deals 125% base AD bonus physical damage to enemies near the target, and creates a field around the target for 2 seconds that slows enemy movement speed by 30% (1.5 second cooldown) (size of field increases with bonus armor). 2700 .
• : +25 armor. Unique Passive – Blocks 10% of the damage from all basic attacks. Unique Passive – Enhanced Movement: +45 movement speed. 1000 .
• : +60 armor, +400 health, -10% damage taken from critical strikes. Unique Passive – Cold Steel: When hit by basic attacks, reduces the attacker's attack speed by 15% for 1 second. Unique Active: Slows the movement speed of nearby enemy units by 35% for 4 seconds (60 second cooldown) (500 range). 2850 .
• : +25 armor, +25 ability power. Unique Passive: Killing a unit grants 0.5 bonus armor, and 0.5 bonus ability power. This bonus stacks up to 30 times. 1200 .
• : +45 armor, +500 health. Unique Passive – Immolate: Deals 25 + (1 × level) magic damage per second to nearby enemies. 2700 .
• : +45 armor. Unique Passive – Cold Steel: When hit by basic attacks, reduces the attacker's attack speed by 15% for 1 second. 1100 .
• : +35 armor, +250 mana, +50 ability power, +10% cooldown reduction. Unique Active – Conduit: Bind to target ally (60 second cooldown). Unique Passive: When within 1000 units of each other, you and your Conduit will generate 1 charge every second, up to 100, with a bonus 4/2 charges whenever you or your ally attack, and 8/4 on spell cast. At 100 charges, causing damage consumes them, increasing your and your ally's ability power by 20% and critical strike chance by 50% for 8 seconds. 2250 .

#### Variable Availability

• SC : +50 armor, +50 magic resistance. Unique Passive: Upon taking lethal damage, restores 30% of maximum health and 30% of maximum mana after 4 seconds of stasis (5 minute cooldown). 2800 .
• H : Unique Active – Battle Cry: Gain 20 armor, 30% movement speed, and 20 magic resistance for 3 seconds (25 second cooldown). +200 health, +125% base health regeneration. Unique Passive: Nearby enemy spellcasts reduce the cooldown of Battle Cry by 1 second. 1015 .
• CH : +25 armor, +225 health, +250 mana, +20% cooldown reduction. Unique Passive – Trap Detection: Nearby stealthed enemy traps are revealed. Unique Active: A stealth-detecting mist grants vision in the target area for 5 seconds, revealing enemy champions that enter for 3 seconds (60 second cooldown). 2080 .
• TC : +50 armor, +50 ability power, +50 magic resistance. Unique Passive – Tenacity: Reduces the duration of stuns, slows, taunts, fears, silences, blinds, and immobilizes by 35%. 2570 .
• S : +50 armor, +300 health, +150% health regen, +10% cooldown reduction. Unique Active: Prevents the closest enemy tower from attacking for 3 seconds (120 second cooldown). This effect cannot be used against the same tower more than once every 8 seconds. Unique Passive – Point Runner: Build up to +20% movement speed over 2 second while near turrets and fallen turrets. 2600 .
• S : +40 armor, +150% base health regen. Unique Passive – Point Runner: Build up to +20% movement speed over 2 second while near turrets and fallen turrets. 1100 .
• SCH : +100 armorUnique Passive: Upon being hit by a basic attack, reflects magic damage back to the attacker equal to 25% of your bonus armor plus 15% of the incoming damage (before being reduced by defenses). 2300 .
• TC : +45 armor, +100 ability power. Unique Passive: Increases ability power by 25%. Unique Active – Stasis: Champion becomes invulnerable and untargetable for 2.5 seconds, but is unable to move, attack, cast spells, or use items during this time (90 second cooldown). 3500 .
• SH : +50 armor, +100 ability power. Unique Active – Stasis: Champion becomes invulnerable and untargetable for 2.5 seconds, but is unable to move, attack, cast spells, or use items during this time (90 second cooldown). 3000 .
• S : +60 armor, +60 magic resist, +150% base health regen. Unique Passive – Point Runner: Build up to +20% movement speed over 2 second while near turrets, fallen turrets and Void Gates. Unique Active: Spawns a Void Gate at target location for 150 seconds. Every 4 seconds the gate makes a that travels down the nearest lane and decays over time. Voidspawn explodes when attacking structures. ignore champions and void targets (150 second cooldown). The first and every fourth voidspawn gain 15% of maximum health as damage (150 second cooldown). 2750 .

### Champion abilities

Note: Only the armor buff effect of these abilities is shown here, to read more information on each of these abilities, follow the link on each of them.

• allows her to enter an egg-state for up to 6 seconds upon reaching 0 health. While in this state, she will receive an armor modifier of −40 / −25 / −10 / +5 / +20.
• increases her armor by 10 / 20 / 30 / 40 / 50 for 5 seconds.
• increases armor by 15 / 17.5 / 20 / 22.5 / 25 + (10 / 11.5 / 13 / 14.5 / 16% bonus armor) to himself and the target ally for 3 seconds.
• increases an allied champion's armor by 30 / 45 / 60 / 75 / 90 for 4 seconds.
• increases his armor by (2 × level) when transform into .
• permanently gains 0.25 bonus armor every time he kills an enemy, up to a maximum of 30.
• increases his armor by 1 / 2 / 3 every second he remains in combat. This bonus stacks up to 10 times. Graves is considered in combat if he has dealt or received damage in the last 3 seconds.
• increases his armor by 5 / 15 / 25 / 35.
• increases his armor by 10 / 20 / 30 / 40 / 50 for 4 seconds.
• increases her armor by 20 / 30 / 40 / 50 / 60 + (20% bonus armor) for 3 seconds, deals damage after that time to units around her, and retains the defensive buff for an additional 3 seconds if any enemy is struck by the blast.
• passively grants armor to himself equal to 10 / 15 / 20 / 25 / 30% of his total armor.
• increases an allied unit's armor by 10 / 15 / 20 / 25 / 30 for 6 seconds.
•  passively increases his armor by 10 / 20 / 30 when he is not under the effects of .
• increases an allied champion's armor by 10 / 15 / 20 / 25 / 30 for as long as the ball is attached to them.
• increases her armor by 1.5 / 2 / 2.5 / 3 / 3.5 for 5 seconds upon attacking or being hit by an enemy, stacks up to 10 times. She can also activate this ability to gain max stacks.
• increases his armor by 40 / 60 / 80 / 100 / 120 for 6 seconds, and deals 15 / 25 / 35 / 45 / 55 + (10% armor) magic damage to enemies who basic attack him.
• Rengar lets out a battle roar, damaging enemies increases his armor by 10 / 15 / 20 / 25 / 30 for 4 seconds. Rengar gains additional 50% armor for each enemy champion or large monster hit.
• grants her 10 / 15 / 20 / 25 bonus armor each times she damages an enemy with an ability or attack for 2 seconds. Subsequent damage will increase the duration by 2 seconds up to a cap of 8 seconds, after where damage will refresh the duration.
• passively increases her armor by 5 / 10 / 15 / 20. This bonus is doubled while she is in Dragon Form (20 / 30 / 40).
• increases his armor by 35 / 50 / 80 for 25 seconds.
• passively grants 10 / 15 / 20 / 25 / 30 bonus armor to himself and 12% of his total armor to himself and nearby allied champions.
• passively generates souls for him to collect, with each soul collected granting 0.75 armor permanently.
• steals instantly 20% of the target's armor. He continues to drain an additional 20% the target's armor over 4 second before decaying 4 seconds after the drain completes.
• increases his armor by 60 / 90 / 120 for 5 seconds upon activation.
• passively grants him 4 / 6 / 8 armor for each nearby enemy champion.
• increases his armor by 15 / 20 / 25 for each enemy champion hit for 8 seconds.

### Masteries

• increases bonus armor and magic resistance by 2.5 / 5 / 7.5 / 10%.
• increases your champion's armor by 2 / 3.5 / 5.
• grants your champion 3 armor and 3 magic resistance for each nearby enemy champion

### Runes

Name Type Tier 1 (Lesser) Tier 2 (Normal) Tier 3 (Greater)
Armor Mark

X X 0.91

205

Seal

0.56

5

0.78

35

1

205

Glyph

X X 0.7

205

Quintessence

2.37

15

3.32

100

4.26

1025

Armor, scaling

(Armor per level)

Mark X X X
Seal

X X 0.16 per level (3)

410

Glyph X X X
Quintessence

X X 0.38 per level (6.84)

1025

## Ways to reduce armor

See armor penetration. Note that armor penetration and armor reduction are different.

## Armor vs. Health

Note: The following information also applies to Magic Resist.

It can be helpful to understand the equilibrium between maximum HP and Armor, which is represented in the graph[1] on the right. The equilibrium line represents the point at which your champion will have the highest Effective Health against that damage type, while the smaller lines represent the baseline progression for each kind of champion from level 1-18 without items. You can also see that for a somewhat brief period in the early game HP is the most gold efficient purchase, however this assumes the enemy team will only have one type of damage. The more equal the distribution of physical/magical damage in the enemy team, the more effective will buying HP be.

There are many other factors which can effect whether you should buy more Armor or HP, such as these key examples:

• Unlike health, increasing armor also makes healing more effective because it takes more effort to remove the unit's health than it does to restore it.
• HP helps you survive both magic and physical damage. Against a team with mainly burst or just low magical damage HP can be more efficient than MR.
• Percentage armor reduction in the enemy team tilts the optimal HP:Armor ratio slightly in the favor of HP.
• Whether or not the enemy is capable of delivering true damage or percent health damage, thus reducing the value of armor and HP stacking respectively.
• The presence of resist or HP steroids built into your champion's kit, such as in or .
• Against sustained damage Life steal and healing abilities can be considered as contributing to your maximum HP (while being mostly irrelevant against burst damage).
• The need to prioritize specific items mainly for their other qualities (regardless of whether or not they contribute towards the ideal balance between HP and resists).

## List of champions' armor

The highest and lowest base armor champions
Champion Level Top 5 champions Bottom 5 champions
Level 1 1. 31.384 armor 1. 16 armor
2. 29.88 armor 2. 17.04 armor
3. 29.54 armor 3. 18.72 armor
4. 29.384 armor 4. 19.012 armor
4.
5. 28.88 armor 5. 19.04 armor
5.
Level 18 1. 104.484 armor 1. 16 armor
2. 103.22 armor 2. 65.5 armor
3. 97.88 armor 3. 68.04 armor
4. 96.72 armor 4. 70.04 armor
4. 4.
5. 94.72 armor 5. 71.04 armor

## Trivia

[Last updated 1/9/2015 on patch 5.16]

• Armor has a gold value of 20g (300/15). This is derived from the basic item for armor .
• One of the biggest amount of armor any champion can obtain, aside from , is 1649.975792 (which reduces physical damage by 94.286%), being a level 18 .

must have:

• All armor runes and masteries
• 6
• cast by a .
• can only use on one target : .
• cast by an .
• can only use on one target : .
• cast by a with the maximum amount of bonus armor.
• can only use on one target : .
• on a with the maximum amount of armor.
• will affect (passive), (aura), and (aura).
• rank 5 on .
Relevant mathematics:
Armor = ((6 × 100 + 15 + 5 + 30 + 0.91 × 9 + 3 × 9 + 0.7 × 9 + 6.84 × 3) × 1.10) + 88.8 = 872.011
Bonus Armor (before ) = (6 × 100 + 15 + 5 + (872.011 × 0.12) + 0.91 × 9 + 3 × 9 + 0.7 × 9 + 6.84 × 3) × 1.10 = 865.316452
Armor = (((6 × 100 + 15 + 5 + 90 + 30 + (872.011 × 0.12) + (25 + 865.316452 × 0.16) + 0.91 × 9 + 3 × 9 + 0.7 × 9 + 6.84 × 3) × 1.10) + 92.1) × 1.30 = 1649.975792

Having an enemy with the same setup use on  will yield a total of 1976.501496 armor. This is the highest possible finite amount of armor (without using metagame effects—see below), and reduces physical damage by 95.184%.

Relevant mathematics:

Armor = (((6 × 100 + 15 + 5 + 90 + 30 + (872.011 × 0.12) + (25 + 865.316452 × 0.16) + 0.91 × 9 + 3 × 9 + 0.7 × 9 + 6.84 × 3) × 1.10) + 92.1) × 1.30 = 1649.975792
Armor = ((6 × 100 + 15 + 5 + 90 + 30 + (872.011 × 0.12) + (25 + 865.316452 × 0.16) + 0.91 × 9 + 3 × 9 + 0.7 × 9 + 6.84 × 3 + (1649.975792 × 0.4)) × 1.10) + 73.4 = 1976.501496

It is still possible to go higher through metagame functions. If a summoner disconnects from the server and is in the fountain, his champion will gain 1000 armor. With the same setup as above, a disconnected  with a disconnected  will have approximately 2779 armor.  cannot exceed this. This reduces physical damage by 96.5%.

, with his effectively infinite stacking, can obtain a maximum of 749999.25 armor off his passive alone. With the same set-up as above, he can obtain a total of about 788575 armor, reducing physical damage by 99.9873205%. If he disconnects, he can obtain up to 789626 armor, reducing it by 99.987337%

## References

1. Should you buy Armor or Health?