Cooldown reduction

Cooldown Reduction (abbreviated as CDR) is a champion statistic that reduces the cooldown of abilities, or the amount of time before an ability can be used again after activation, by a percentage. There are some items that separately reduce the cooldown for summoner spells or item active abilities, but do not grant cooldown reduction.

Cooldown reduction can be granted by items,, and runes. CDR stacks additively and is capped at 40%, which can be increased to 45% with the rune.

Cooldown reduction is determined at the moment an ability is activated. Increasing/decreasing cooldown reduction while the skill is on cooldown will not affect the cooldown.

Cooldown reduction does not apply to:
 * Static cooldowns
 * Item active abilities (e.g. )
 * Item passive effects with cooldowns (e.g. )
 * Summoner spells.

Although not a basic item, is the item from which the cooldown reduction gold value of  per % cooldown reduction is derived.

Champion Abilities
Some champions have abilities that decrease their cooldowns by a flat amount, either their base cooldown or current cooldown, or entirely refresh their cooldown. Base reduction occurs before cooldown reduction takes effect while flat reduction occurs after cooldown reduction takes effect. By using those, a champion can circumvent the 40% cooldown reduction cap.
 * Depending on built-in reduction type:
 * Base (applies before CDR)
 * Flat (applies after CDR)
 * Percent (applies to base / current / total cooldown)
 * Refresh (cooldown is immediately reduced to 0)

Base reduction

 * base cooldown is halved if it kills the target.
 * base cooldown is halved if it kills the target.
 * base cooldown is reduced by 1 second if it hits a target, stacking up to 2 times.
 * base cooldown is reduced to seconds while casting inside of.

Flat reduction

 * cooldown is reduced by seconds each time Amumu is hit by an attack.
 * reduces all of Ezreal's cooldowns by 1 second if it strikes an enemy unit.
 * cooldown is reduced by 3 seconds if it hits an enemy unit.
 * cooldown is reduced by 1 second for every autoattack.
 * cooldown is reduced by seconds every time she damages an enemy champion with an ability, and by  seconds for a basic attack.
 * reduces all her abilities' cooldowns by 15 seconds whenever an enemy champion dies within 3 seconds of Katarina dealing damage to them.
 * cooldown is reduced by 1 second for each of 's strikes, and by 2 seconds against champions.
 * cooldown is reduced by 1 second for every autoattack.
 * cooldown is reduced by seconds by marking a new target with.
 * innate cooldown is reduced by 1 second for every autoattack.
 * cooldown is reduced by 1 second for every autoattack.
 * cooldown is reduced by seconds if he manages to pick up his axe after using the ability.
 * cooldown is reduced by seconds for every autoattack.
 * cooldown is reduced by seconds for each successful autoattack, and by 1 second against champions.
 * cooldown is reduced by 1 second if she throws the.
 * 's basic attacks reduce the cooldowns of his basic abilities by seconds, and instantly granting 1 charge of.
 * cooldown is reduced by 3 seconds upon hitting an enemy.
 * cooldown is reduced by 1 second for every critical strike.
 * reduces his other abilities' cooldowns by 1 second for each strike (for a maximum of 3 seconds reduction).
 * cooldown is reduced by 2 seconds when his hits an enemy champion.
 * innate cooldown is reduced by 4 seconds whenever he uses an ability.
 * on activation, reduces all of Zilean's other basic abilites' cooldowns by 10 seconds.

Percentage reduction

 * cooldown is reduced by 60% if the first cast hits a monster.
 * cooldown is reduced by % if he can catch it when its return (scales with level).
 * cooldown is reduced by 60% if he picks up his boulder after using the ability.
 * passive component allows him to reduce the current cooldown on all of his basic abilities by 70% for every kill or assist he scores.
 * base cooldown is reduced by 70% while it's currently higher if it kills a unit, or if hits an enemy marked as.
 * decreases cooldowns of her basic abilities by %.
 * base cooldown is reduced by.
 * cooldown is reduced by 1% for every he has.

Cooldown refreshing

 * cooldown is refreshed if the target is afflicted with the Moonlight debuff from.
 * (rank 3) cooldown is refreshed if it kills enemy champion.
 * cooldown is refreshed if he catches a.
 * cooldown is refreshed is she enters.
 * cooldown is refreshed if it kills a unit.
 * cooldown is refreshed if it kills at least one target.
 * cooldown is refreshed if he gets a champion kill or assist.
 * cooldown is refreshed by using his other abilities.
 * cooldown is refreshed whenever she gets a champion kill or assist.
 * cooldown is refreshed if an enemy dies while affected by.

Active Ability Items

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 * Notes
 * Multiple copies of the same active ability item share a global cooldown.
 * Purchasing yet another copy while the already owned ones are still on CD will make the newest one's sync up with the others'.

Trivia
Last updated: November 21, 2017 – V7.23

One cost and efficient way to reach maximum CDR (45%) is:
 * Having both and, and reaching level 10, giving you 15% CDR.
 * Then by buying the which will provide 10% CDR.
 * And finally by purchasing a 20% CDR–item.

The most cooldown reduction any champion can obtain at level 1 with is 20%. To achieve this you must :
 * Have the rune which will provide 5% CDR.
 * Buy (5% CDR)
 * Have the from the  (10% CDR)


 * Relevant mathematics:
 * 20%

Cooldown reduction Abklingzeitverringerung Reducción de enfriamiento Réduction des délais de récupération Skrócenie czasu odnowienia Сокращение перезарядки 冷却缩减