Leech

Leech or lifesteal effects take away life or other resource like mana from a target and giving it to the caster. The resource received does not have to correspond with the damage dealt, and in many cases a character could get a part of the health back, or a multiplication of the damage dealt.

Leech/lifesteal is not the same as drain or bleed, but the effects are similar, and can sometimes be combined.

An example of a leech skill is the Barbarian's Bloodthirst.