- Added a notification message to the case when not enough legal targets are left to tap during the cost payment that includes tapping a certain number of cards.

forge-gui/src/main/java/forge/player/HumanCostDecision.java

@@ -1157,6 +1157,7 @@ public class HumanCostDecision extends CostDecisionMakerBase {
         }
 
         if (c > typeList.size()) {
+            controller.getGui().message("Not enough valid cards left to tap to pay the cost.", "Cost payment invalid");
             return null; // not enough targets anymore (e.g. Crackleburr + Smokebraider tapped to get mana)
         }