- For the successor stat, see ability haste.
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Cooldown Reduction (CDR) was a statistic that reduced the cooldown of champion abilities. It did not affect static cooldowns nor on-target cooldowns, unless it was otherwise stated. Other forms of cooldown reduction existed for items, summoner spells, and specifically ultimate abilities.
Cooldown reduction was gained by items, runes, and buffs. It was capped at 40%, increased to 45% with 
Cosmic Insight.
The formula for cooldown reduction was: Base Cooldown × (1 − CDR ÷ 100)
Gold Value
- Cooldown reduction had a gold value of
26.67 per point.
Increasing cooldown reduction[]
Items[]
Unnamed Cooldown Reduction[]
Various items granted cooldown reduction.
Named Cooldown Reduction[]
- Unique – Haste: Grants an additional 10% cooldown reduction.
Runes[]
Neutral Buffs[]
Other cooldown reduction[]
Ultimate abilities[]
- Notes
- Ultimate Hunter and Cloudbringer's Grace stacked additively with each other while regular cooldown reduction stacked multiplicatively with them.
Items[]
- Notes
- Cosmic Insight and Ingenious Hunter stack additively with each other.
- Multiple copies of the same active ability item, and unique named active share a global cooldown.
- Purchasing yet another copy while the already owned ones are still on cooldown will make the newest one's sync up with the others'.
Summoner spells[]
Trivia[]
Highest CDR[]
Last updated: December 15th, 2019 – V9.24
One cost efficient way to have reached maximum CDR (45%) was:
- Having both Cosmic Insight and Transcendence, and reaching level 10, giving 15% CDR.
- Then by buying the Ionian Boots of Lucidity which will provide 10% CDR.
- And finally by purchasing a 20% CDR–item.
- Frozen Heart – 2700
- Iceborn Gauntlet – 2700
- Hextech GLP-800 – 2800
- Nashor's Tooth – 3000
- Black Cleaver – 3000
- Archangel's Staff – 3200
- Luden's Echo – 3200
- Essence Reaver – 3300
- Trinity Force – 3773
The most cooldown reduction any champion could have obtained at level 1 with 
500 was 15%. To achieve this a champion must:
- Have had the Cosmic Insight rune which will provide 5% CDR.
- Have had the Crest of Insight from the Blue Sentinel (10% CDR)
- Relevant mathematics:
- 5% + 10% = 15%
| Offensive |  Ability power ·  Attack damage ·  Attack speed ·  Critical strike chance ·  Critical strike damage ·  Armor penetration ·  Magic penetration ·  Life steal ·  Omnivamp · Physical vamp ·  True damage
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|---|---|
| Defensive |  Heal and shield power ·  Health ·  Health regeneration ·  Armor ·  Magic resistance ·  Tenacity ·  Slow resist
|
| Utility |  Ability haste ·  Energy ·  Energy regeneration ·  Mana ·  Mana regeneration  Movement speed ·  Range
|
| Other |  Experience ·  Gold generation
|