Life Stealer is a Medal in Bug Fables. It reduces an ally's attack by 1, but allows them to heal 1/2 of the damage they deal to enemies, rounded down to minimum of 1.
Attacks that deal 0 damage still heal 1 HP. It is recommended that other attack-boosting medals be equipped in order to undo the reduced attack from this medal. It should be noted that multi-hit skills will heal only once, but a multi-action command skill, like Frost Relay, will heal for each action command completed. Additionally, if this medal is paired with Life Cast, its healing effect will be reduced from 1/2 to 1/4 of damage dealt.