Ability power

Ability power (AP) is a champion statistic that increases the effectiveness of most abilities. It stacks additively.

Effects that benefit from ability power receive a bonus based on a certain percentage of a champion's current ability power. For example, if a spell deals 100 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).