Cooldown reduction (abbreviated as CDR) is a hero stat that reduces the cooldown of abilities, or the amount of time you must wait before an ability can be used again once you activated it, by a percentage.
Cooldown reduction is granted by items, buffs and talents, as well as some passive abilities.
Cooldown reduction stacks additively. For example, if you have 5% cooldown reduction from talents and 15% cooldown reduction from Dark Shield, you will have 20% cooldown reduction.
- Cooldown reduction cannot be increased beyond 40%
Cooldown reduction is determined at the moment an ability is activated. Increasing/decreasing your cooldown reduction while the skill is on cooldown will not affect the cooldown.
Cooldown reduction does not apply on most item active abilities (except for Spiritual Purification Dagger and Nice Rod) such as that of Dark Shield or item passive effects with cooldowns such as that of Reiji Maigo. Most sources of cooldown reduction also do not apply on summoner spells and most of an Innate Ability (Static Cooldown) unless specifically stated.