Every distinct wording since 2010, newest first.
June 10, 2022 · Commander Legends: Battle for Baldur’s Gate
If a delayed triggered ability created by a resolving spell or ability refers to X, X is not defined in the text of that triggered ability, and the spell or ability that created it had a value of X chosen for any of its costs, the value of X for the triggered ability is the same as the value of X for the spell of ability that created it.
September 25, 2020 · Zendikar Rising
Some objects use the letter Y in addition to the letter X. Y follows the same rules as X.