An ability that states which zones it doesn’t function in functions everywhere except for the specified zones, even outside the game and before the game begins.
July 12, 2019 · Core Set 2020
An object’s ability that allows a player to pay an alternative cost rather than its mana cost or otherwise modifies what that particular object costs to cast functions on the stack.
July 16, 2010 · Magic 2011
rule 113.6c not present in this release
February 1, 2010 · Worldwake
If an effect allows a player to "choose new targets" for a spell or ability, the player may leave any number of the targets unchanged, even if those targets would be illegal. If the player chooses to change some or all of the targets, the new targets must be legal.