Text (7th/8th/9th): If you control a creature, damage that would reduce your life total to less than 1 reduces it to 1 instead.
If this effect is applied when you lose life due to unprevented damage. All the damage got dealt (for purposes of triggers), but the player's life total is not reduced by the full amount of the damage. [WotC Rules Team 1998/10/18]
It reduces your life total to 1, not the damage to 1. [D'Angelo 1999/01/23]
It does not do anything to prevent or modify loss of life from anything other than unprevented damage. A spell or ability that causes loss of life directly (without causing damage) is applied as normal. [D'Angelo 2003/09/08]