Lifesteal

Lifesteal allows the attacking unit to gain health when damaging an enemy, which includes any attack modifier with physical damage or magical damage. The lifesteal ability can be gained via items, passive abilities or the auras of other units.

The amount of health a unit gains from lifesteal is calculated by a percentage of the actual damage done to the attacked unit. This means it does not heal for overkill damage dealt to a unit, so if an attack's damage exceeded the target's current health and killed it, the heal is based on the target's remaining health. The only exceptions to this rule are 's Spell Lifesteal and, which always restore the full amount of health, no matter how much a unit had left when lifestealed off.

Unique Attack Modifiers
Lifesteal as a Unique Attack Modifier is the most common form of lifesteal and can be used by both melee and ranged units. With the exception of 's Unholy Rage ability, they are all passive abilities. Items that give this type of lifesteal are:

These items do not stack with each other. The one in the highest priority slot overrides the others.

Stacking sources
These lifesteal effects fully stack with every other source of lifesteal and every other attack modifier, except with themselves.

Interactions with other abilities

 * Lifesteal is calculated after critical strikes, which means that it increases the amount of life you steal.
 * Illusions do not benefit from lifesteal or lifesteal auras. However, the particle effects of lifesteal do show. This is to make lifesteal not instantly give away that they are illusions.
 * Secondary targets of instant attacks can be lifestealed off as long as the instant attack is able to carry attack modifiers. Therefore, and  are excluded.
 * If an attack modifier directly adds the damage it deals to the attack damage (like bashes), its damage can lifesteal:

1 Cannot lifesteal when originated from Unique Attack Modifiers.

Spell Lifesteal
Spell Lifesteal only comes into effect when using a spell that deals damage, healing for a certain percentage of the damage dealt by the spell. Spell Lifesteal stacks fully with every other source of lifesteal and every other attack modifier, except with itself.

Pseudo-Lifesteal
Certain lifesteal effects work quite a bit different from regular lifesteal. Their mechanics are unique to the spell they are provided by.