History of CR 702.1a
Every distinct wording since 2010, newest first.
May 3, 2019 · War of the Spark
If an effect refers to a “[keyword ability] cost,” it refers only to the variable costs for that keyword.
January 25, 2019 · Ravnica Allegiance
If an effect refers to a "[keyword ability] cost," it refers only to the variable costs for that keyword.
September 30, 2016 · Kaladesh
If an effect refers to a “[keyword ability] cost,” it refers only to the variable costs for that keyword.
February 1, 2010 · Worldwake
rule 702.1a not present in this release