Ghostfire Blade - fixed that it can't be played without full available mana (#6698);

Mage/src/main/java/mage/abilities/costs/CostAdjuster.java

@@ -8,5 +8,14 @@ import mage.game.Game;
  */
 public interface CostAdjuster {
 
+    /**
+     * Must check playable and real cast states.
+     * Example: if it need stack related info (like real targets) then must check two states (game.inCheckPlayableState):
+     * 1. In playable state it must check all possible use cases (e.g. allow to reduce on any available target and modes)
+     * 2. In real cast state it must check current use case (e.g. real selected targets and modes)
+     *
+     * @param ability
+     * @param game
+     */
     void adjustCosts(Ability ability, Game game);
 }