* Squelch - Fixed that it was causing a ClassCastException (fixes #3396).

Mage.Server.Plugins/Mage.Player.AI/src/main/java/mage/player/ai/ComputerPlayer.java

@@ -727,7 +727,23 @@ public class ComputerPlayer extends PlayerImpl implements Player {
             }
             return target.isChosen();
         }
-
+        if (target.getOriginalTarget() instanceof TargetActivatedAbility) {
+            List<StackObject> stackObjects = new ArrayList<>();
+            for (UUID uuid : ((TargetActivatedAbility) target).possibleTargets(source.getSourceId(), source.getControllerId(), game)) {
+                StackObject stackObject = game.getStack().getStackObject(uuid);
+                if (stackObject != null) {
+                    stackObjects.add(stackObject);
+                }
+            }
+            while (!target.isChosen() && !stackObjects.isEmpty()) {
+                StackObject pick = stackObjects.get(0);
+                if (pick != null) {
+                    target.addTarget(pick.getId(), source, game);
+                    stackObjects.remove(0);
+                }
+            }
+            return target.isChosen();
+        }
         throw new IllegalStateException("Target wasn't handled. class:" + target.getClass().toString());
     }
 

Mage.Sets/src/mage/cards/t/TolariaWest.java

@@ -28,12 +28,12 @@
 package mage.cards.t;
 
 import java.util.UUID;
-import mage.constants.CardType;
 import mage.abilities.common.EntersBattlefieldTappedAbility;
 import mage.abilities.keyword.TransmuteAbility;
 import mage.abilities.mana.BlueManaAbility;
 import mage.cards.CardImpl;
 import mage.cards.CardSetInfo;
+import mage.constants.CardType;
 
 /**
  *
@@ -42,11 +42,11 @@ import mage.cards.CardSetInfo;
 public class TolariaWest extends CardImpl {
 
     public TolariaWest(UUID ownerId, CardSetInfo setInfo) {
-        super(ownerId,setInfo,new CardType[]{CardType.LAND},"");
+        super(ownerId, setInfo, new CardType[]{CardType.LAND}, "");
 
         // Tolaria West enters the battlefield tapped.
         this.addAbility(new EntersBattlefieldTappedAbility());
-        // {tap}: Add {U} to your mana pool.
+        // {T}: Add {U} to your mana pool.
         this.addAbility(new BlueManaAbility());
         // Transmute {1}{U}{U}
         this.addAbility(new TransmuteAbility("{1}{U}{U}"));

Mage.Tests/src/test/java/org/mage/test/cards/abilities/oneshot/counterspell/CounterActivatedAbilityTest.java

@@ -0,0 +1,50 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.mage.test.cards.abilities.oneshot.counterspell;
+
+import mage.constants.PhaseStep;
+import mage.constants.Zone;
+import org.junit.Test;
+import org.mage.test.serverside.base.CardTestPlayerBase;
+
+/**
+ *
+ * @author LevelX2
+ */
+public class CounterActivatedAbilityTest extends CardTestPlayerBase {
+
+    /**
+     * The Card 'Sqelch' is bugged. In a game versus a human I tried to counter
+     * a Toloria West activation as well as a Elspeth Sun's Champion activation
+     * to make the game roll back to the begining of the turn and to show a pop
+     * pup with an error message which I cannot post here due to forum
+     * limitations.
+     *
+     */
+    @Test
+    public void testSquelch() {
+        // +1: Create three 1/1 white Soldier creature tokens.
+        // -3: Destroy all creatures with power 4 or greater.
+        // -7: You get an emblem with "Creatures you control get +2/+2 and have flying."
+        addCard(Zone.BATTLEFIELD, playerA, "Elspeth, Sun's Champion", 1);
+
+        // Counter target activated ability
+        addCard(Zone.HAND, playerB, "Squelch", 1); // Instant {1}{U}
+        addCard(Zone.BATTLEFIELD, playerB, "Island", 2);
+
+        activateAbility(1, PhaseStep.PRECOMBAT_MAIN, playerA, "+1");
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerB, "Squelch");
+
+        setStopAt(1, PhaseStep.BEGIN_COMBAT);
+        execute();
+
+        assertGraveyardCount(playerB, "Squelch", 1);
+        assertPermanentCount(playerA, "Soldier", 0);
+
+    }
+
+}

Mage/src/main/java/mage/target/common/TargetActivatedAbility.java

@@ -73,7 +73,7 @@ public class TargetActivatedAbility extends TargetObject {
         }
         StackObject stackObject = game.getStack().getStackObject(id);
         return stackObject != null && stackObject.getStackAbility() != null && stackObject.getStackAbility().getAbilityType() == AbilityType.ACTIVATED
-                && filter.match(((ActivatedAbility) stackObject), game);
+                && filter.match(((ActivatedAbility) stackObject.getStackAbility()), game);
     }
 
     @Override
@@ -104,7 +104,7 @@ public class TargetActivatedAbility extends TargetObject {
         for (StackObject stackObject : game.getStack()) {
             if (stackObject.getStackAbility().getAbilityType() == AbilityType.ACTIVATED
                     && game.getState().getPlayersInRange(sourceControllerId, game).contains(stackObject.getStackAbility().getControllerId())
-                    && filter.match(((ActivatedAbility) stackObject), game)) {
+                    && filter.match(((StackAbility) stackObject), game)) {
                 possibleTargets.add(stackObject.getStackAbility().getId());
             }
         }