In League of Legends, the spell vamp stat heals the user for a percentage of the damage dealt by abilities. The amount healed is calculated after enemy magic resistance, armor and other abilities that reduce damage are taken into account. Abilities that apply on-hit effects or modify basic attacks do not benefit from spell vamp. Activated items and summoner spells are also affected by spell vamp.
Area of effect abilities apply 33 percent of the characters listed spell vamp per enemy hit. Certain abilities have unique rules for applying spell vamp, such as Ahri's Fox-Fire ability, with which each projectile is considered a single-target ability and take advantage of 100 percent of spell vamp. Damage-over-time abilities take full advantage of spell vamp. Effects that reduce healing reduce the effect of spell vamp.
There are four items, four champion abilities, one mastery and one rune that increase or produce the spell vamp effect. The items Guinsoo's Rageblade, Hextech Revolver, Hextech Gunblade and Will of the Ancients provide spell vamp and can be used together. Akali's passive ability Twin Disciplines, Lee Sin's ability Iron Will, Morgana's passive ability Soul Siphon and Ryze's ultimate ability Desperate Power all grant spell vamp as well. The mastery Vampirism and the rune Quintessence of Spell Vamp grant a small amount of spell vamp.