A player can’t pay a cost without having the necessary resources to pay it fully. For example, a player with only 1 life can’t pay a cost of 2 life, and a permanent that’s already tapped can’t be tapped to pay a cost. See rule 202, “Mana Cost and Color,” and rule 602, “Activating Activated Abilities.”
May 3, 2019 · War of the Spark
If an effect causes a player to gain life or lose life, that player’s life total is adjusted accordingly.
January 25, 2019 · Ravnica Allegiance
If an effect causes a player to gain life or lose life, that player's life total is adjusted accordingly.
February 1, 2014 · Born of the Gods
If an effect causes a player to gain life or lose life, that player’s life total is adjusted accordingly.
September 30, 2011 · Innistrad
If an effect causes a player to gain life or lose life, that player's life total is adjusted accordingly.
June 17, 2011 · Commander 2011
If an effect causes a player to gain life or lose life, that player’s life total is adjusted accordingly.
April 1, 2011 · Duel Decks: Knights vs. Dragons
If an effect causes a player to gain life or lose life, that player's life total is adjusted accordingly.
October 1, 2010 · Scars of Mirrodin
If an effect causes a player to gain life or lose life, that player’s life total is adjusted accordingly.
July 16, 2010 · Magic 2011
If an effect causes a player to gain life or lose life, that player's life total is adjusted accordingly.
February 1, 2010 · Worldwake
Damage may have one or more of the following results, depending on whether the recipient of the damage is a player or permanent, the characteristics of the damage's source, and the characteristics of the damage's recipient (if it's a permanent).