You don't lose the game for having 0 or less life.
: You gain 1 life.
Cumulative upkeep
When this enters the battlefield, draw a card.
: Prevent all damage that would be dealt this turn by target creature you control. That creature gets +0/+X until end of turn, where X is its converted mana cost.
,, Sacrifice a creature of the chosen type: this deals 3 damage to target creature or player.
: Target creature can't be blocked by Walls this turn. If an opponent controls a wall, draw a card.
: Target creature you control gets +3/+3 until end of turn. Destroy it at the beginning of the next end step. A creature destroyed this way can't be regenerated.