An Immortal's statistics showing a Spirit Vamp of 9%.
Spirit Vamp, or Mana Steal in some other games, replenishes the Mana of the attacker for a percentage of the damage dealt. For example, if an Immortal has 10% Spirit Vamp and deals 100 points of damage to the target, the Immortal regains 10 points of Mana. Spirit Vamp caps at 50%.