118.1.
Each player begins the game with a life total of 20.
118.1a
In a Two-Headed Giant game, each team begins the game with a shared life total of 30
instead; see rule 810, «Two-Headed Giant Variant.»
118.1b
In a Vanguard game, each player begins the game with a starting life total of 20, as modified
by his or her vanguard card‘s life modifier. See rule 902, «Vanguard.»
118.1c
In a Commander game, each player begins the game with a starting life total of 40 instead;
see rule 903, «Commander.»
118.1d
In an Archenemy game, the archenemy begins the game with a starting life total of 40
instead; see rule 904, «Archenemy.»
118.2.
Damage dealt to a player normally causes that player to lose that much life. See rule 119.3.
118.3.
If an effect causes a player to gain life or lose life, that player‘s life total is adjusted accordingly.
118.4.
If a cost or effect allows a player to pay an amount of life greater than 0, the player may do so
only if his or her life total is greater than or equal to the amount of the payment. If a player pays
life, the payment is subtracted from his or her life total; in other words, the player loses that much
life. (Players can always pay 0 life.)
118.4a
If a cost or effect allows a player to pay an amount of life greater than 0 in a Two-Headed
Giant game, the player may do so only if his or her team‘s life total is greater than or equal to
the total amount of life both team members are paying for that cost or effect. If a player pays
life, the payment is subtracted from his or her team‘s life total. (Players can always pay 0 life.)
118.5.
If an effect sets a player‘s life total to a specific number, the player gains or loses the necessary
amount of life to end up with the new total.
118.6.
If a player has 0 or less life, that player loses the game as a state-based action. See rule 704.
118.7.
If an effect says that a player can‘t gain life, that player can‘t exchange life totals with a player
who has a higher life total; in that case, the exchange won‘t happen. In addition, a cost that involves
having that player gain life can‘t be paid, and a replacement effect that would replace a life gain
event affecting that player won‘t do anything.
118.8.
If an effect says that a player can‘t lose life, that player can‘t exchange life totals with a player
who has a lower life total; in that case, the exchange won‘t happen. In addition, a cost that involves
having that player pay life can‘t be paid.
118.9.
Some triggered abilities are written, «Whenever [a player] gains life, . . . .» Such abilities are
treated as though they are written, «Whenever a source causes [a player] to gain life, . . . .»
Example: A player controls Ajani?s Pridemate, which reads “Whenever you gain life, you
may put a +1/+1 counter on Ajani?s Pridemate,” and two creatures with lifelink. The
creatures with lifelink deal combat damage simultaneously. Ajani?s Pridemate?s ability
triggers twice.