Lifesteal - Target heals, or recovers HP, for a % of the damage dealt during an attack.
Type: effect - Category: Health
See also: | 
Heal | 
Health Loss | 
Lifesteal | 
Max HP Boost | 
Repair | 
Resurrection | 
Unhealable Damage
Lifesteal is an alternative form of Healing and a typical ability of 
Dark Heroes. The healing is based on the damage dealt. This means that the more damage the hero deals, the more hit points they get back.
Heroes who deal a lot of damage benefit most from Lifesteal. The obvious disadvantage of Lifesteal is, of course, that no healing is possible if the hero cannot deal damage. Reasons can be shields like 
Invincibility on the target, or the hero is 
Diseased or not able to attack at all. For example if he or she is 
Frozen.
The effect of Lifesteal is easy to recognize by a "swarm of green +", which floats back from the hit enemy to the attacker.
Vampiric Runes can also give heroes who do not have a natural Lifesteal trait this effect. These Runes return up to 10% of the damage caused to the wearer of the rune as hit points with every hit. The percentage values of several Runes and natural Lifesteal stacks; in other words, the percentage values are added together.
Lifesteal and Vampiric Runes do not work for Construct heroes that have the 
Construct trait but work for 
Living Stone heroes, like 
Stone Fist.
Debuffs That Block Lifesteal
There are Debuffs that block Lifesteal. They are mainly the same as for Healing. For example:
Heroes
The following heroes can Lifesteal:
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Epic Immortality Through Death (Trait): Allies gain 25% lifesteal and Foresight at the start of each turn. Undead allies gain double of each. (This trait replaces the trait 'Immortality Through Death' when the Epic is unlocked.) Immortality Through Death (Trait): Self and Undead allies Lifesteal 25% more damage and gain Foresight at the start of every turn.
Dwarven Vitality (Trait): Self and Dwarf allies' Max HP is boosted by % and Lifesteal a % of the damage dealt.
Vampiric (Trait): Lifesteals a % of the damage dealt.
Feed the Flames (Trait): Self and Fire allies heal a % of the damage dealt.
Fire Mend (Special Attack): Buffs team +ATK, then does a Ranged Fire attack on all enemies that Lifesteals for the team.
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Soul Devour (Special Attack): Ranged Dark attack that Lifesteals and steals all Buffs from the target, adding them to Hopper.
Deal With the Devil (Special Attack): Borrow a % of health from an enemy to heal self, but the enemy will be healed the amount stolen in 2 rounds. (Enemy receives a Devil's IOU buff.)
Windows to the Soul (Trait): All attacks are Shield-Piercing and will heal [25%/50%] of damage dealt (% healing increased with Skill). The percentage value depends on the rank (I-II) of the trait.
Beastly Hunger (Trait): When on a team with Solaris, Lifesteals 50% of damage dealt.
Waterlogged Field (Special Attack): Ranged Water attack on all enemies, lifestealing for all allies. Reduces enemy healing and a chance to add Drenched for 3 turns.
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Siphoning Slice (Special Attack): Melee Spirit attack in which a % of the damage dealt returns as Lifesteal for the team. Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Sapping Vines (Special Attack): Ranged Nature attack on all enemies for [40% ATK] base damage and absorbs health for allies, reduces enemy healing, and Grows allies Plants for 3 turns.
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Envious Rampage (Special Attack): Melee Physical attack on target and 2 random enemies that Lifesteals and has a chance to steal a Buff on hit.
Bog Blessing (Special Attack): Ranged Nature attack on all enemies, healing all allies for a percentage of damage dealt. Lowers SKL, Max Health, and applies Swamped to all enemies hit. Starts Powered.
Unbridled Loyalty (Special Attack): Buffs allies for 3 turns, redirecting [51%] damage to Moriko. When damage is retaliated this way, Moriko lifesteal reflects a part of the damage back to the attacker. Starts Powered.
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Vampiric Barrage (Special Attack): Ranged Physical attack on all enemies that Lifesteals.
Vampiric Shurikens (Special Attack): Ranged Physical attack on target and 1 random enemy (2 random enemies at level 20+) that Lifesteals.
Sapping Venom (Trait): Allies' Ranged Physical attacks have a chance to apply Venom on hit and heal percent of damage dealt.
Cheers Mate (Special Attack): Melee Physical attack that Lifesteals.
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.
Epic Heroes with Lifesteal:
Veth's Mace (Epic): Chance to deal 3x damage and Lifesteal for the team.
Ultimate Skins with Lifesteal:
Soulless Scourge (Trait): Immune to Poison, Venom, Wound, and Disease. Lifesteals 25% of damage dealt.