If a player can’t pay or chooses not to pay the Applied Cost, they cannot perform the associated Game Action.
§ 204.4.c Core Rules PDF (officieel)
§ 204 Costs paid in this way might be:
§ 204.4 Applied Costs: These Costs are applied to one or more Game Actions, and typically take the form of a passive ability with a Cost within Instructions preceded by “must.” Example: Mageseeker Investigator reads in part “Opponents must pay [A] for each unit beyond the first to move multiple units to my b…
