* Some minor chnages.

Mage.Sets/src/mage/cards/c/ContestedWarZone.java

@@ -55,7 +55,7 @@ public class ContestedWarZone extends CardImpl {
     private static final FilterAttackingCreature filter = new FilterAttackingCreature("Attacking creatures");
 
     public ContestedWarZone(UUID ownerId, CardSetInfo setInfo) {
-        super(ownerId,setInfo,new CardType[]{CardType.LAND},null);
+        super(ownerId, setInfo, new CardType[]{CardType.LAND}, null);
 
         // Whenever a creature deals combat damage to you, that creature's controller gains control of Contested War Zone.
         this.addAbility(new ContestedWarZoneAbility());
@@ -102,7 +102,7 @@ class ContestedWarZoneAbility extends TriggeredAbilityImpl {
 
     @Override
     public boolean checkTrigger(GameEvent event, Game game) {
-        DamagedPlayerEvent damageEvent = (DamagedPlayerEvent)event;
+        DamagedPlayerEvent damageEvent = (DamagedPlayerEvent) event;
         if (damageEvent.isCombatDamage()) {
             Permanent permanent = game.getPermanent(event.getSourceId());
             if (damageEvent.getPlayerId().equals(getControllerId()) && permanent != null && permanent.isCreature()) {
@@ -137,7 +137,7 @@ class ContestedWarZoneEffect extends ContinuousEffectImpl {
 
     @Override
     public boolean apply(Game game, Ability source) {
-        Permanent permanent = (Permanent) source.getSourceObjectIfItStillExists(game);
+        Permanent permanent = game.getPermanent(source.getSourceId());
         UUID controllerId = (UUID) game.getState().getValue(source.getSourceId().toString());
         if (permanent != null && controllerId != null) {
             return permanent.changeControllerId(controllerId, game);

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

@@ -29,6 +29,7 @@ package org.mage.test.cards.abilities.keywords;
 
 import mage.constants.PhaseStep;
 import mage.constants.Zone;
+import org.junit.Ignore;
 import org.junit.Test;
 import org.mage.test.serverside.base.CardTestPlayerBase;
 
@@ -512,4 +513,45 @@ public class FlashbackTest extends CardTestPlayerBase {
         assertExileCount(playerA, dReturn, 1);
         assertPermanentCount(playerA, bSable, 1);
     }
+
+    /**
+     * I can play Force of Will with flashback paying his alternative mana cost.
+     * The ruling say no to it, because we only can choose one alternative cost
+     * to a spell, and the flashback cost is already an alternative cost.
+     */
+    @Test
+    @Ignore
+    public void testSnapcasterMageSpellWithAlternateCost() {
+        addCard(Zone.BATTLEFIELD, playerA, "Island", 1);
+        addCard(Zone.BATTLEFIELD, playerA, "Forest", 1);
+        // When Snapcaster Mage enters the battlefield, target instant or sorcery card in your graveyard gains flashback until end of turn.
+        // The flashback cost is equal to its mana cost.
+        addCard(Zone.HAND, playerA, "Snapcaster Mage", 2); // Creature{1}{U}
+
+        // You may pay 1 life and exile a blue card from your hand rather than pay Force of Will's mana cost.
+        // Counter target spell.
+        addCard(Zone.GRAVEYARD, playerA, "Force of Will");
+
+        addCard(Zone.HAND, playerB, "Lightning Bolt", 1);
+        addCard(Zone.BATTLEFIELD, playerB, "Mountain", 1);
+
+        castSpell(1, PhaseStep.PRECOMBAT_MAIN, playerA, "Snapcaster Mage");
+        setChoice(playerA, "Force of Will");
+
+        castSpell(1, PhaseStep.POSTCOMBAT_MAIN, playerB, "Lightning Bolt", "Snapcaster Mage");
+        activateAbility(1, PhaseStep.POSTCOMBAT_MAIN, playerA, "Flashback", null, "Lightning Bolt");
+        addTarget(playerA, "Lightning Bolt");
+
+        setStopAt(1, PhaseStep.END_TURN);
+        execute();
+
+        assertPermanentCount(playerA, "Snapcaster Mage", 0);
+        assertGraveyardCount(playerA, "Snapcaster Mage", 1);
+
+        assertGraveyardCount(playerA, "Force of Will", 1);
+        assertGraveyardCount(playerB, "Lightning Bolt", 1);
+
+        assertLife(playerA, 20);
+
+    }
 }

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

@@ -72,6 +72,9 @@ public class AddManaOfAnyColorEffect extends BasicManaEffect {
             String mes = String.format("Select color of %d mana to add it to your mana pool", this.amount);
             ChoiceColor choice = new ChoiceColor(true, mes, game.getObject(source.getSourceId()));
             if (controller.choose(outcome, choice, game)) {
+                if (choice.getColor() == null) {
+                    return false;
+                }
                 Mana createdMana = choice.getMana(amount);
                 if (createdMana != null) {
                     checkToFirePossibleEvents(createdMana, game, source);

Mage/src/main/java/mage/abilities/effects/common/ruleModifying/PlayLandsFromGraveyardEffect.java

@@ -11,8 +11,6 @@ import mage.constants.SubLayer;
 import mage.game.Game;
 import mage.players.Player;
 
-import java.util.UUID;
-
 public class PlayLandsFromGraveyardEffect extends ContinuousEffectImpl {
 
     public PlayLandsFromGraveyardEffect() {
@@ -33,11 +31,10 @@ public class PlayLandsFromGraveyardEffect extends ContinuousEffectImpl {
     public boolean apply(Game game, Ability source) {
         Player player = game.getPlayer(source.getControllerId());
         if (player != null) {
-            for (UUID cardId: player.getGraveyard()) {
+            for (Card card : player.getGraveyard().getCards(game)) {
-                Card card = game.getCard(cardId);
+                if (card != null && card.isLand()) {
-                if(card != null && card.isLand()){
                     PlayLandFromGraveyardAbility ability = new PlayLandFromGraveyardAbility(card.getName());
-                    ability.setSourceId(cardId);
+                    ability.setSourceId(card.getId());
                     ability.setControllerId(card.getOwnerId());
                     game.getState().addOtherAbility(card, ability);
                 }

Mage/src/main/java/mage/game/draft/DraftCube.java

@@ -30,9 +30,7 @@ package mage.game.draft;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
-
 import mage.cards.Card;
-import mage.cards.repository.CardCriteria;
 import mage.cards.repository.CardInfo;
 import mage.cards.repository.CardRepository;
 import mage.util.RandomUtil;