Every champion starts with 0 ability power, and level-ups do not grant additional ability power.
Ability power can be increased with items, abilities and runes, it stacks additively, and each bonus point acquired directly affects its statistic.
Effects that benefit from ability power receive a bonus based on a certain percentage of the current ability power. For example, if a spell deals 100 (+20% AP) damage and a champion has 50 ability power, the spell's damage will increase by 10. In-game, spell descriptions do not display the percentage, but do display the resulting bonus; the previous example would display as 100 (+10).
- Ability power has a gold value of
21.75 per point.
Ability power as scaling
Many champion abilities use the champion's ability power to calculate the magnitude of that ability.
The following 17 champions do not have 
ability power ratios on any on their abilities: 
Aatrox, 
Camille, 
Darius, 
Draven, 
Garen, 
Kalista, 
Kayn, 
Kindred, 
Kled, 
Olaf, 
Pyke, 
Riven, 
Talon, 
Urgot, 
Vayne, 
Xayah, 
Zed.
Items
Runes
Increasing ability power
Items
Specific to 
Viktor
Champion abilities
Runes
Neutral Buffs
Decreasing ability power
Champion abilities
Trivia
- The ability with the largest AP ratio is Annie's Summon Tibbers, with a maximum AP ratio of (+ 515% AP) counting initial cast of (+ 65% AP) and the target taking damage from all 45 ticks of Tibbers aura damage ((+ 10% AP) per tick).
- The second and third bounces of Nami's Ebb and Flow scale exponentially, however the low base ratio means it will not beat other spells at normal levels of AP.
Last updated: January 30, 2019, patch V9.2
- Disregarding Veigar, Thresh, and Gathering Storm, and assuming Kleptomancy gives no biscuits; the highest attainable ability power by a champion on Summoner's Rift is a level 18 Viktor with 2314.656 AP.
- Runes:
- Kleptomancy
- Biscuit Delivery
- Absolute Focus
- Waterwalking
- Adaptive Force
- Adaptive Force
-
- Buffs:
- Viktor will need to have Ornn alongside him.
- Hand of Baron
- Three Infernal Drake buffs empowered with the Empowered Aspect of the Dragon buff
- Pilfered Potion of Rouge
- Travel Size Elixir of Sorcery
- Elixir of Sorcery
-
- Items:
- Mejai's Soulstealer with 25 stacks
- Perfect Hex Core
- Rabadon's Deathcap
- Rabadon's Deathcrown
- Seraph's Embrace
- Spellbinder activated at 100 stacks
-
- Viktor's AP:
Last updated: January 30, 2019, patch V9.2
- The highest attainable ability power by a champion at level 1 is 86 AP on Viktor. This applies only if it is possible to get at level 1 a Pilfered Potion of Rouge and a Travel Size Elixir of Sorcery through Kleptomancy.
- Runes:
- Kleptomancy
- Absolute Focus
- Waterwalking
- Adaptive Force
- Adaptive Force
-
- Items:
Relevant mathematics:
| Offensive | Ability power ·  Attack damage ·  Attack speed ·  Critical strike chance ·  Critical strike damage ·  Armor penetration ·  Magic penetration ·  Life steal ·  Spell vamp ·  True damage
|
|---|---|
| Defensive |   Heal and shield power ·  Health ·  Health regeneration ·  Armor ·  Magic resistance ·  Tenacity ·  Slow resist
|
| Utility |  Cooldown reduction ·  Energy ·  Energy regeneration ·  Mana ·  Mana regeneration
|
| Other |  Experience ·  Gold generation ·  Movement speed ·  Range
|
