* Meld - Fixed a bug that produced an exception if while the meld ability was on the stack, one of the permanents to meld left the battlefield meanwhile.

Mage.Tests/src/test/java/org/mage/test/cards/abilities/keywords/MeldTest.java

@@ -163,4 +163,47 @@ public class MeldTest extends CardTestPlayerBase {
         assertHandCount(playerB, 0);
 
     }
+
+    /**
+     * With Hanweir Garrison and Hanweir Battlements in your control put Hanweir
+     * Battlements' ability in the stack to transform(i.e. meld). In answer to
+     * that, return to hand Hanweir Garrison. Resolve Hanweir Battlements
+     * ability.
+     *
+     * Expected result: The ability fizzles.
+     *
+     * Actual results: A NPE error is lauched.
+     */
+    @Test
+    public void testReturnToHand() {
+        addCard(Zone.BATTLEFIELD, playerA, "Mountain", 5);
+
+        // Whenever Hanweir Garrison attacks, put two 1/1 red Human creature tokens onto the battlefield tapped and attacking.
+        // <i>(Melds with Hanweir Battlements.)</i>
+        addCard(Zone.BATTLEFIELD, playerA, "Hanweir Garrison"); // Creature 2/3 {2}{R}
+
+        // {T}: Add {C} to your mana pool.
+        // {R},{T}: Target creature gains haste until end of turn.
+        // {3}{R}{R},{T}: If you both own and control Hanweir Battlements and a creature named Hanweir Garrison, exile them, then meld them into Hanweir, the Writhing Township.
+        addCard(Zone.BATTLEFIELD, playerA, "Hanweir Battlements"); // Land
+
+        // Brisela, Voice of Nightmares  9/10
+        // Flying, First strike, Vigilance, Lifelink
+        // Your opponents can't cast spells with converted mana cost 3 or less.
+        addCard(Zone.BATTLEFIELD, playerB, "Island", 1);
+        // Return target creature to its owner's hand.
+        addCard(Zone.HAND, playerB, "Unsummon", 1); // Instant {U}
+
+        activateAbility(1, PhaseStep.PRECOMBAT_MAIN, playerA, "{3}{R}{R}");
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerB, "Unsummon", "Hanweir Garrison", "{3}{R}{R}");
+
+        setStopAt(1, PhaseStep.BEGIN_COMBAT);
+        execute();
+
+        assertGraveyardCount(playerB, "Unsummon", 1);
+
+        assertPermanentCount(playerA, "Hanweir Battlements", 1);
+        assertHandCount(playerA, "Hanweir Garrison", 1);
+
+    }
 }

Mage/src/main/java/mage/abilities/effects/common/MeldEffect.java

@@ -79,32 +79,36 @@ public class MeldEffect extends OneShotEffect {
             filter.add(new NamePredicate(meldWithName));
             TargetPermanent target = new TargetControlledCreaturePermanent(filter);
             Set<UUID> meldWithList = target.possibleTargets(sourceId, source.getControllerId(), game);
+            if (meldWithList.isEmpty()) {
+                return false; // possible permanent has left the battlefield meanwhile
+            }
             UUID meldWithId;
             if (meldWithList.size() == 1) {
                 meldWithId = meldWithList.iterator().next();
-            }
+            } else {
-            else {
                 controller.choose(Outcome.BoostCreature, target, sourceId, game);
                 meldWithId = target.getFirstTarget();
             }
             // Exile the two permanents to meld.
             Permanent sourcePermanent = game.getPermanent(sourceId);
             Permanent meldWithPermanent = game.getPermanent(meldWithId);
-            sourcePermanent.moveToExile(null, "", sourceId, game);
+            if (sourcePermanent != null && meldWithPermanent != null) {
-            meldWithPermanent.moveToExile(null, "", sourceId, game);
+                sourcePermanent.moveToExile(null, "", sourceId, game);
-            // Create the meld card and move it to the battlefield.
+                meldWithPermanent.moveToExile(null, "", sourceId, game);
-            Card sourceCard = game.getExile().getCard(sourceId, game);
+                // Create the meld card and move it to the battlefield.
-            Card meldWithCard = game.getExile().getCard(meldWithId, game);
+                Card sourceCard = game.getExile().getCard(sourceId, game);
-            if (!sourceCard.isCopy() && !meldWithCard.isCopy()) {
+                Card meldWithCard = game.getExile().getCard(meldWithId, game);
-                meldCard.setOwnerId(controller.getId());
+                if (!sourceCard.isCopy() && !meldWithCard.isCopy()) {
-                meldCard.setTopHalfCard(meldWithCard, game);
+                    meldCard.setOwnerId(controller.getId());
-                meldCard.setbottomHalfCard(sourceCard, game);
+                    meldCard.setTopHalfCard(meldWithCard, game);
-                meldCard.setMelded(true);
+                    meldCard.setbottomHalfCard(sourceCard, game);
-                game.addMeldCard(meldCard.getId(), meldCard);
+                    meldCard.setMelded(true);
-                game.getState().addCard(meldCard);
+                    game.addMeldCard(meldCard.getId(), meldCard);
-                meldCard.moveToZone(Zone.BATTLEFIELD, sourceId, game, false);
+                    game.getState().addCard(meldCard);
+                    meldCard.moveToZone(Zone.BATTLEFIELD, sourceId, game, false);
+                }
+                return true;
             }
-            return true;
         }
         return false;
     }