Recover from KO.Description
Life is a Wht Mag spell in Final Fantasy IX for Dagger, Eiko, and Beatrix, used to restore a KO'd ally back to life with critical HP both mid-battle and in the menu, or for instantly defeating the undead. Life responds to Reflect and the spell would work with Return Magic were enemies to use it on the player party, but no enemy does.
Life has the same animation in battle as Phoenix Down, but calculates the HP the revived gains differently (the revived comes back to life with 5%+ of their maximum HP); for revival purposes however, the two are nigh interchangeable.
The earliest the player can get it is from the Mythril Rod for Dagger, bought from the Aerbs Mountains summit station. Cachusha is an exceedingly rare Chocobo Hot and Cold treasure, but the earliest the player can partake in the minigame is when Dagger is not in the party, and when the player resumes control of her, she is at the Aerbs Mountains, anyway. Eiko starts with the Golem Flute, so she can have Life as soon as she joins the party on the Conde Petie Mountain Path. Beatrix knows the spell natively.
The formula for how much HP Life revives with is as follows:
Life revives one ally at critical health, likely slightly better than the effect of using a Phoenix Down. Life can be empowered by equipping Concentrate, while Phoenix Down cannot be empowered by equipping a Chemist. Phoenix Downs can be fairly plentiful, especially if the player is stealing from every encounter to power up Zidane's Thievery for the endgame, but Life also only costs 8 MP to use.
Life can be used offensively to dispatch undead enemies in a single cast for a fairly low MP cost. This is useful during the time the party is heading to the Iifa Tree with two healers in the formation. Though they may not look it, the Mistodons as part of this segment are also undead, as is the boss Soulcage. Later on, the party can also face Whale Zombies when exploring the world, which are easiest dispatched with Life.
Once Eiko learns Phoenix and Full-Life, they become her superior revival methods unless MP is an issue; Phoenix when there are numerous KO'd allies, and Full-Life when there is just one. Life is Dagger's sole revival spell, which remains useful until the end of the game.