Only creatures can be modified

forge-ai/src/main/java/forge/ai/ability/CountersAi.java

@@ -101,6 +101,7 @@ public abstract class CountersAi extends SpellAbilityAi {
         Card choice = null;
 
         if (type.equals("P1P1")) {
+            // TODO look for modified
             choice = ComputerUtilCard.getBestCreatureAI(list);
 
             if (choice == null) {

forge-game/src/main/java/forge/game/card/Card.java

@@ -3491,6 +3491,9 @@ public class Card extends GameEntity implements Comparable<Card>, IHasSVars {
     }
 
     public final boolean isModified() {
+        if (!isCreature()) {
+            return false;
+        }
         if (this.isEquipped() || this.hasCounters()) {
             return true;
         }