Leech (D20 Modern Feat)
From D&D Wiki
The character can transfer the life force of others with touch.
Benefit: As a special use of the Power (healing or regeneration) skill you manipulate the life essence of others and your own. Whenever you touch another there is a 50% chance that you drain 1d4 per 2 character levels of hit points from that person and the other 50% chance is that the effect will be reversed and you will lose 1d4 hit points per 2 character levels. All hit points gained in this way are considered temporary hit points, which last for 1 minute after, that can go above the targets total hit points. Healing or Regeneration checks made for purposes other than controlling the effect above.