Lifesteal

Lifesteal is a mechanic which heals a player by a portion of the damage they deal to an opponent. There are two main types of lifesteal, each with an associated stat: Bullet Lifesteal, which returns a portion of the bullet damage dealt, and Spirit Lifesteal, which returns a portion of the spirit damage dealt. Bullet and Spirit Lifesteal are calculated identically, but are affected by different items.

Formula

Despite being presented in-game as +X% Bullet/Spirit Lifesteal, different sources of lifesteal stack multiplicatively, not additively. With $n$ different sources of the same category of lifesteal, final lifesteal $L_{F}$ is given by:

$L_{F}=1-\prod _{i=1}^{n}(1-L_{i})$

where $L_{i}$ is the lifesteal provided by the $i$th source. Bullet and Spirit Lifesteal are calculated independently of each other, but both use the same formula.

Example

With 10% Bullet Lifesteal from Crippling Headshot and 35% Bullet Lifesteal from Leech, the player's final bullet lifesteal is:

$L_{F}=1-(1-0.10)\times (1-0.35)=41.5\%$

This means that any time the player deals bullet damage to any opponent (including denizens), they will immediately be healed by 41.5% of the damage dealt. Note that the in-game user interface is inconsistent in how it rounds the final lifesteal percentage.

Bullet Lifesteal

Bullet Lifesteal returns a percentage of all outgoing bullet damage to the player as health.

Sources

List of items

Name	Cost	Category	Stat change
Active Reload	1,250	Weapon	+20% Bullet Lifesteal
Heroic Aura	3,000	Weapon	+20% Bullet Lifesteal
Crippling Headshot	6,200	Weapon	+10% Bullet Lifesteal
Vampiric Burst	6,200	Weapon	+100% Bullet Lifesteal
Bullet Lifesteal	1,250	Vitality	+28% Bullet Lifesteal
Leech	6,200	Vitality	+35% Bullet Lifesteal

Spirit Lifesteal

Spirit Lifesteal returns a percentage of all outgoing spirit damage to the player as health.

Sources

List of items

Name	Cost	Category	Stat change
Soul Shredder Bullets	1,250	Weapon	+20% Spirit Lifesteal
Crippling Headshot	6,200	Weapon	+10% Spirit Lifesteal
Spiritual Overflow	6,200	Weapon	+10% Spirit Lifesteal
Enduring Spirit	500	Vitality	+10% Spirit Lifesteal
Spirit Lifesteal	1,250	Vitality	+23% Spirit Lifesteal
Leech	6,200	Vitality	+35% Spirit Lifesteal
Infuser	500	Spirit	+20% Spirit Lifesteal
Slowing Hex	1,750	Spirit	+10% Spirit Lifesteal
Diviner's Kevlar	6,200	Spirit	+20% Spirit Lifesteal
Mystic Reverb	6,200	Spirit	+14% Spirit Lifesteal

Soul Shredder Bullets

The debuff applied to opponents by Soul Shredder Bullets behaves differently from all other lifesteal items. It does not affect the user's Spirit Lifesteal stat, nor is it factored into the formula above; instead, it adds a flat +20% spirit lifesteal against an affected target while the debuff is active. For example, if a player had Soul Shredder Bullets, Enduring Spirit (+10%), and Leech (+35%), their spirit lifesteal against a target affected by Soul Shredder Bullets would be:

$L_{F}=[1-(1-0.10)\times (1-0.35)]+0.20=61.5\%$

Their spirit lifesteal against a target not affected by Soul Shredder Bullets would instead be 41.5% (equal to their Spirit Lifesteal stat).

Melee Lifesteal

Main articles: Melee Lifesteal, Lifestrike

Melee Lifesteal is not a stat. The item Melee Lifesteal and its upgrade Lifestrike both provide a passive ability which heals the user by a percentage of their melee damage dealt, but they behave differently from Bullet and Spirit Lifesteal. These abilities activate for one melee attack, then go on cooldown for several seconds, during which no further health can be regained from melee attacks; Bullet and Spirit Lifesteal are always active and have no associated cooldowns. These items also grant a flat healing bonus on activation, and are less effective against non-heroes, neither of which is true of Bullet and Spirit Lifesteal.