Tenacity (or Crowd Control Reduction) is a stat that reduces the duration of all incoming 
crowd control status effects except 
airborne, 
drowsy, 
kinematics, 
nearsight, 
stasis, and 
suppression. The stat is the percentage by which the duration is reduced. The duration cannot be reduced below 0.3 − 0.625 seconds (based on when the game adds / removes the buff). The duration of the crowd control is calculated at the time of application and does not change if the tenacity changes.
Increasing tenacity
Tenacity can be increased with champion abilities, items, runes, and summoner spells, stacking either 
multiplicatively or 
additively depending on the combination of the effects.
Items
Elixirs
Champion abilities
Runes
Summoner Spells
Game Modes
Reducing Tenacity
Tenacity can be reduced to negative values, causing crowd control to last longer.
Champion Abilities
Ornn's Bellows Breath and Call of the Forge God apply Brittle, which is a unique status effect that reduces tenacity by 30%.
Items
- Anathema's Chains reduces the Nemesis' tenacity by 20% while at maximum stacks of Vendetta. This stacks multiplicatively with Brittle for a total of -56% tenacity.
Monsters
- Rift Scuttler has -100% tenacity, doubling the duration of crowd control effects applied to her. This stacks additively with Brittle for a total of -130% tenacity.
Stacking
The tenacity stat is build up from sub-stats that internally are referred to as "modifiers". For the lack of naming scheme, the LoL Wiki simply refers to these as types, from A to E. Combination of effects in the same type will stack additively, while combination of multiple types will stack multiplicatively.
The mathematics regarding the total tenacity is as follows:
1 - (1 - (A1 + A2 + ...)) × (1 - (B1 + B2 + ...)) × (1 - (C1 + C2 + ...)) × (1 - (D1 + D2 + ...)) × (1 - (E1 + E2 + ...))
| Source | |
|---|---|
| Type A |
|
| Type B | |
| Type C |
|
| Type D | |
| Type E |
For instance, a champion owns 
Mercury's Treads and has 
Legend: Tenacity at maximum stacks, and a nearby enemy champion affects them with 
Anathema's Chains' tenacity reduction. The sum of their tenacity is calculated as follows:
- Type A Tenacity modifiers = 30% + -20%
- Type E Tenacity modifier = 30%
- Final Tenacity = 1 - (1 - Type A Tenacity modifier) × (1 - Type E Tenacity modifier)
Trivia
- Until patch V1.0.0.118, Tenacity was an unnamed effect unique to Mercury's Treads. That patch promoted the effect to a champion statistic and added three new items: Cloak and Dagger, Eleisa's Miracle and Moonflair Spellblade (all later removed). Tenacity from multiple sources did not stack, similar to Enhanced Movement. In Season Three there was an item overhaul, named item effects were introduced, and Tenacity was reverted to an item effect. In V3.01, all sources of crowd control reduction were changed to say "Tenacity" and Tenacity was reintroduced as a champion statistic.
- Until Season Three, Tenacity's in-game icon was the same as the icon used for Cho'Gath's Vorpal Spikes and Baron Nashor's passive. Between the introduction of season 3 changes and V3.01, it shared the same icon as the Tenacious mastery. As of V3.01, it no longer has an icon in the buff bar.
- Prior to the Preseason of 2021, a website news post was made that announced that Tenacity would reduce the duration of knockups. However, the change was confirmed to have been cancelled.[1]
- Prior to his VGU in patch V11.12, Dr. Mundo's Burning Agony granted himself 30% Tenacity which was additive with other "Champion Tenacity" buffs such as Brittle.
- Prior to V3.04, Singed's Insanity Potion granted himself 10 / 15 / 20% Tenacity.
Last updated: June 24, 2021, patch V11.13
- The biggest amount of Tenacity you can obtain is 99.265% with Garen.
- 1 - (0.4 × 0.3 × 0.25 × 0.35 × 0.7) = 99.265%
- With this amount of tenacity, Nasus' Wither (longest crowd control in the game) would only last 0.03675 seconds. The minimum crowd control duration prevents this.
- In comparison, Nasus' Wither would last 7.8 seconds if the target has no tenacity and is Brittled and affected by Anathema's Chains.
- In comparison,
- Note that this amount of tenacity can only be achieved briefly with Courage wearing off almost immediately, and with Cleanse and Silvermere Dawn which grant a temporary buff.
| Offensive |  Ability power ·  Attack damage ·  Attack speed ·  Critical strike chance ·  Critical strike damage ·  Armor penetration ·  Magic penetration ·  Life steal ·  Omnivamp · Physical vamp ·  True damage
|
|---|---|
| Defensive |  Heal and shield power ·  Health ·  Health regeneration ·  Armor ·  Magic resistance · Tenacity ·  Slow resist
|
| Utility |  Ability haste ·  Energy ·  Energy regeneration ·  Mana ·  Mana regeneration
|
| Other |  Experience ·  Gold generation ·  Movement speed ·  Range
|
