Lifesteal

Lifesteal is a League of Legends stat that heals you for a percentage of the damage your basic attacks deal. A champion with 20% lifesteal who hits for 100 damage recovers 20 health, letting auto-attackers sustain through fights and trades.

It is a staple stat for marksmen and many fighters, who rely on it to stay healthy while dealing damage over time. Lifesteal applies only to basic attacks, which is what distinguishes it from omnivamp and ability-based vamp. Healing-reduction effects like Grievous Wounds counter it, so it is strong but not unconditional sustain.