Damage modifier

Damage modifiers refer to the buffs or debuffs to a unit that causes it to deal or receive increased or decreased damage. These are percentage values. They don't add extra flat damage but modify all damage normally done. These buffs or debuffs are only received by champion abilities, neutral buffs, on-hit effects from items and masteries.

Damage dealt modifier[ | ]

These are buffs that allow the champion that has them to deal increased or decreased magic or physical damage from autoattacks, abilities, item's actives and Ignite. The raw value from the attack or ability is increased or decreased by the modifier and then applied to the target.

All damage dealt modifiers stack multiplicatively. Since multiplication is commutative, the order is irrelevant. So if Talon uses an autoattack on a CC'd champion just after using a maxed Cutthroat on it, while affected by Urgot's Zaun-Touched Bolt Augmenter, his autoattack's damage will be modified by 107.525% (110% × 115% × 85%).

Champion abilities[ | ]

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

Corki's Hextech Shrapnel Shells grants his basic attacks additional 10% true damage.
Kayle's Reckoning blasts her target and slows it for 4 seconds. While the target is slowed, Kayle inflicts 6% / 7% / 8% / 9% / 10% more damage to the target from all sources.
LeBlanc's Mimic allows her to recast a spell with 10% / 25% / 40% increased damage.
Pantheon's Certain Death grants Spear Shot 50% additional damage to targets below 15% health.
Poppy's Diplomatic Immunity allows her to focus intensely on one single target for 6 / 7 / 8 seconds to deal 20% / 30% / 40% increasing her damage to it from all sources.
Riven's Wind Slash deals 2.66% increased damage for each 1% health the targets are missing (maximizing at ~200% increased damage when targets are at 25% health or less).
Sejuani's Northern Winds deal 50% increased damage against targets affected by Frost and Permafrost.
Shaco's Backstab allows him to deal 20% increased damage when striking a unit from behind with his autoattacks or abilities.
Sona's Hymn of Valor grants her Power Chord 100% additional damage.
Swain's Torment afflicts his target, dealing damage to them over time and causing Swain to deal 8% / 11% / 14% / 17% / 20% increased damage to it for 4 seconds from all damage sources.
Syndra's Dark Sphere deals 15% increase damage against champions when at maximum rank.
Talon's Cutthroat allows him to blink to his target and deal 3% / 6% / 9% / 12% / 15% increased damage to it for the next 3 seconds.
Talon's Mercy allows his autoattacks to deal 10% increased damage if his target is slowed, stunned, immobilized or suppressed.
Vayne's Tumble grants her next attack 10% / 20% / 30% / 40% / 50% increased damage.
Volibear's Frenzy deals 1% increased damage for each 1% health the target is missing.
Yorick's Unholy Covenant grants him 5% increased basic attack damage for each ghoul currently summoned.

Masteries[ | ]

Havoc Havoc increases your champion's physical and magical damage by 0.5% / 1% / 1.5%.
Executioner Executioner increases all damage dealt by your champion by 5% to enemies under 50% of their max health.

Decreasing damage dealt[ | ]

Champion abilities[ | ]

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

Sona's Aria of Perseverance enhances her Power Chord, to debuff her target to deal 20% less damage for 4 seconds.
Urgot's Zaun-Touched Bolt Augmenter makes his autoattacks and Acid Hunter reduce all damage that his target deals by 15% for 2.5 seconds.

Summoner Spell[ | ]

Exhaust reduces autoattack damage by 70% and ability/item damage by 35% for 2.5 seconds.

Damage received modifier[ | ]

These are buffs or debuffs that allow the champion that have them to receive increased or decreased magic or physical damage from autoattacks, abilities, item's actives and Ignite. The final value from the attack or ability is increased or decreased by the modifier and then directly applied to the target's health.

Armor and magic resistance damage reduction percentage count as one source of damage received modifier against physical and magical damage respectively. For example, a champion with 300 armor has 75% damage reduction from physical damage.

Damage reduction from armor and magic resistance and from any other sources stack multiplicatively.

Increasing damage received[ | ]

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

Champion abilities[ | ]

Vladimir's Hemoplague affects all targets hit to receive 12% increased damage from all sources for the next 5 seconds.

Decreasing damage received[ | ]

Champion abilities[ | ]

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

Alistar's Unbreakable Will grants him 50% / 60% / 70% damage reduction for 7 seconds.
Galio's Idol Of Durand Idol Of Durand grants him 50% damage reduction while channeling for up to 2 seconds.
Garen's Courage places a defensive shield on himself, decreasing all damage taken by a 30% for 2 / 3 / 4 / 5 / 6 seconds.
Gragas' Drunken Rage channels for 1 second and then receives 10% / 12% / 14% / 16% / 18% reduced damage for 20 seconds.
Kassadin's Void Stone reduces all magic damage taken by 15%.
Katarina's Shunpo to grant her 15% damage reduction for 3 seconds after blinking.
Kha'Zix's Evolved Void Assault Evolved Void Assault takes 40% reduced damage while in stealth.
Maokai's Vengeful Maelstrom creates a great vortex of natural energy on a nearby area reducing non-tower damage done to allied champions in the area by 20% until toggled off.
Poppy's Valiant Fighter reduces all damage that exceeds 10% of her current health by 50%.
Shen's Shadow Dash reduces all physical damage by 50% from taunted enemies.
Yorick's Unholy Covenant grants him 5% damage reduction for each ghoul currently summoned.

Items[ | ]

Leviathan grants the wearer 15% damage reduction when at 20 stacks.
Ninja Tabi grants the wearer 10% damage reduction from physical autoattacks.
Odyn's Veil grants the wearer 10% reduced magic damage.

Masteries[ | ]

Honor Guard Honor Guard reduces all damage taken (besides true damage) by 0.5% / 1% / 1.5%.

Damage immunity[ | ]

There are some instances in the game where a champion is immune to receiving any kind of damage (including true damage) for a few seconds.

Champions[ | ]

Kayle's Intervention grants the target ally champion damage immunity for 2 / 2.5 / 3 seconds.
Poppy's Diplomatic Immunity grants her damage immunity from all sources except from her target for 6 / 7 / 8 seconds.

Items[ | ]

Zhonya's Hourglass grants the user damage immunity for 2 seconds.

Flat Damage Reduction[ | ]

Several champions have abilities that reduce damage by a flat amount. Flat damage reduction is factored in after armor or magic resistance^{(verify? Sion's page disagrees)}. This makes it significantly better the more resistances you have. In addition, periodic damage effects will have each tick of damage reduced. For example, Malzahar's Malefic Visions ticks 8 times, so 1 flat damage reduction would reduce its total damage by 8.

Flat damage reduction does not work against true damage.

Champions[ | ]

Amumu's Tantrum provides 2 / 4 / 6 / 8 / 10 physical flat damage reduction.
Fizz's Nimble Fighter provides Error: Parameter '3' is not accepted. flat damage reduction against auto-attacks.
Sion's Feel No Pain provides a 40% chance to ignore Error: Parameter '3' is not accepted. flat damage against auto-attacks.