Life Steal

Life Steal is a frequently encountered trait on items (generally weapons). It allows the user to replenish their Life with damage dealt against the enemy.

The steal comes from how much damage you do to the monster. So 5% Life Stolen will return 5% of the damage that you do to a monster to your health as life, adjusted by the amount of Drain Effectiveness the monster has.

There are several magical suffixes that enable Life Steal, so the effect may occasionally be found on Magic and Rare Items.

Diablo I/Hellfire
Life Steal only works on melee attacks.

Life steal is only available in 3 forms; 3% Life Steal, 5% Life Steal, and Life Stealing. The Life Stealing affix can only be found on The Undead Crown possessed by the Skeleton King, but it offers 0-12.5% life stolen per hit, and stacks with life steal on the hero's weaponry. 3% Life Steal and 5% Life Steal however, cannot stack if a Bard from Hellfire were to try to dual wield weapons with those suffixes. Only the most powerful of the combination applies.

Diablo II/Lord of Destruction
Life and Mana Steal work on melee and physical ranged attacks.

Life Steal gains some potency, and is generally among the affixes wanted by Melee and Ranged physical attack heroes alike. They can spawn on Weapons, Jewelry, Circlets, and Gloves. In the case of a hero possessing 2 weapons, such as a Barbarian or an Assassin dual wielding Claw-class weaponry, the life steal is specific to the weapon possessing that affix.

Some things to keep in consideration about Life Steal:
 * Life Steal works on only Physical damage. All other forms of damage will not aid a hero's leeching.
 * Monsters have varying resistances to Life/Mana Steal, in the form of Drain Effectiveness. As the number listed on a monster's Drain Effectiveness descends, so too does the effectiveness of Life/Mana Steal.
 * In comparison to Normal, changing to Nightmare or Hell Difficulty will lower the effectiveness of Life/Mana Steal. This is further reduced by a monster's Drain Effectiveness, which is also affected by difficulty. From strongest to weakest, the stealing adjustments are:
 * Normal: 100%
 * Nightmare: 50%
 * Hell: 33%

Diablo III/Reaper of Souls
Life Steal returned in Diablo III, although it was nerfed from Diablo II/Lord of Destruction. For one thing, the maximum life stealing possible was 6% from a Two-Handed Weapon, and 3% for all other sources. To complicate matters, only the Barbarians had access to another source of this: their Mighty Belts had the potential to roll life steal. This, in turn, lead to different legitimate caps of life stealing for different classes. From top to bottom they were: Unlike in Diablo II/Lord of Destruction, reaching a higher level penalizes a hero's effective Life Steal. Comparing to one who has just started his/her journey, life steal will be reduced to: The restriction above was not planned until the pre-expansion patch, but before that point, this affix had too much staying power. As the game increased your healing power the higher your damage (DPS in the game's case) increased, this affix allowed a hero to ignore his Life, armor, and resistances almost completely. As long as the hero had enough to survive one major blow in endgame content, he/she was considered a fully qualified tank, but with much higher damaging capabilities. This was quickly spread and became the dominant force in all ingame builds, and the ones who played this style felt that this was the most efficient way to play, making others who never wished to use it feel as if they were 'gimped' players.
 * Barbarian : 9% Life Steal, 6% from their Weapons, and 3% from their Mighty Belts (+3% Bloodthirst)
 * Monk : 6% Life Steal, 3% from wielding 2 weapons with the affix, or 6% from a Two-Handed Weapon.
 * Demon Hunter : 6% Life Steal if they choose to dual wield Hand Crossbows, 3% otherwise (+15% Shadow Power)
 * Wizard : 6% if they choose to go with a Two-Handed Weapon, 3% otherwise (+1.5% Blood Magic rune of Magic Weapon spell)
 * Witch Doctor : 6% if they choose to go with a Two-Handed Weapon, 3% otherwise.
 * Levels 60-69: 10%
 * Level 70: 0% (that is no life stealing)

As a result, the effectiveness of Life Steal drops past level 60, and the moment a hero reaches level 70, it ceases to work at all, being replaced by the Life on Hit stat wherever possible. Consequently, as of the pre-expansion patch, Life Steal has been made non-existent, with the notable exception of equipment found before the above mentioned patch. As a part of this change, all player skills that granted Life Steal in any way or returned part of damage inflicted as Life were either reworked to grant Life per Hit / Life per resource spent, removed entirely or limited to X% of maximum health per application.

Life Steal on Monsters
Heroes should be warned, however, that they are not the only players who can steal life from their opponents. The following monsters were readily allowed access to life stealing:
 * The Skeleton King (multiplayer Diablo/Hellfire only, 100%)
 * Vampires with their Life Steal Missile

In addition, in Diablo III/Reaper of Souls, Champion, Rare and Unique monsters could possess the Vampiric affix, which allowed them to heal while damaging the nephalem in combat. Fortunately, this was the only source of monster healing in Diablo III, removed altogether in later patches, only some Unique monsters keeping it as a legacy trait.