Yep, Baily pretty much summed it up. A card that can be used against your opponents or in favor of you depending on your situation.
Against your opponent: Poison a creature, Lobotomize a Creature, use in conjunction with Antimatter to heal you AND hit your opponent.
For you: Cast on a big creature to heal you for massive amounts; use in conjunction with Heal or Archangels to keep health up.