Life drain is a special ability of vampire lords. It emerges when a stack of Vampire Lords attack an enemy creature, and before they retaliate. Life drain ability causes killed Vampire Lords to rise from the dead for the same amount of health points the Vampire Lord inflicted damage. Additionally, it heals the top unit with the remainder. In other words, for every 40 points of damage the stack of Vampire Lords causes, one Vampire Lord rises from the dead. Life drain funtions in a similar way to Animate Dead spell (or Resurrection).
As the ability name suggests, target attacked creature stack must be considered to be alive. This means that the ability does not work on non-living creatures, which considers undead, golems and elementals.
Creatures with life drain special ability: