Subrule · Chapter 2
cr:2.2.4a
An effect that increases or reduces the cost of an object does not modify the cost property of that object. Effects that modify cost are only applied as part of the process for playing or activating that object.[5.1.6]
Example: An effect that reduces the cost to play a card does not change the cost property of that card in any way - it only changes the calculation of the resource cost when that card is being played.