* GUI: meld cards improves:

* added images download for melds cards (#9660);
 * added switch card side button to view a meld part;
 * fixed NPE and other errors on card side switching;
 * added meld cards support in test render dialog;

Mage.Client/src/main/java/mage/client/dialog/TestCardRenderDialog.java

@@ -33,6 +33,7 @@ import mage.game.mulligan.Mulligan;
 import mage.game.mulligan.MulliganType;
 import mage.game.permanent.Permanent;
 import mage.game.permanent.PermanentCard;
+import mage.game.permanent.PermanentMeld;
 import mage.players.Player;
 import mage.players.StubPlayer;
 import mage.util.CardUtil;
@@ -111,7 +112,7 @@ public class TestCardRenderDialog extends MageDialog {
     }
 
     private PermanentView createPermanentCard(Game game, UUID controllerId, String code, String cardNumber, int powerBoosted, int toughnessBoosted, int damage, boolean tapped, boolean transform, List<Ability> extraAbilities) {
-        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber);
+        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber, false);
         ExpansionInfo setInfo = ExpansionRepository.instance.getSetByCode(code);
         CardSetInfo testSet = new CardSetInfo(cardInfo.getName(), setInfo.getCode(), cardNumber, cardInfo.getRarity(),
                 new CardGraphicInfo(cardInfo.getFrameStyle(), cardInfo.usesVariousArt()));
@@ -126,24 +127,31 @@ public class TestCardRenderDialog extends MageDialog {
             extraAbilities.forEach(ability -> permCard.addAbility(ability));
         }
 
-        PermanentCard perm = new PermanentCard(permCard, controllerId, game);
+        // meld card must be a special class, see CardUtils.putCardOntoBattlefieldWithEffects
-        if (transform) {
+        PermanentCard permanent;
-            // need direct transform call to keep other side info (original)
+        if (permCard instanceof MeldCard) {
-            TransformAbility.transformPermanent(perm, permCard.getSecondCardFace(), game, null);
+            permanent = new PermanentMeld(permCard, controllerId, game);
+        } else {
+            permanent = new PermanentCard(permCard, controllerId, game);
         }
 
-        if (damage > 0) perm.damage(damage, controllerId, null, game);
+        if (transform) {
-        if (powerBoosted > 0) perm.getPower().setBoostedValue(powerBoosted);
+            // need direct transform call to keep other side info (original)
-        if (toughnessBoosted > 0) perm.getToughness().setBoostedValue(toughnessBoosted);
+            TransformAbility.transformPermanent(permanent, permCard.getSecondCardFace(), game, null);
-        perm.removeSummoningSickness();
+        }
-        perm.setTapped(tapped);
+
-        PermanentView cardView = new PermanentView(perm, permCard, controllerId, game);
+        if (damage > 0) permanent.damage(damage, controllerId, null, game);
+        if (powerBoosted > 0) permanent.getPower().setBoostedValue(powerBoosted);
+        if (toughnessBoosted > 0) permanent.getToughness().setBoostedValue(toughnessBoosted);
+        permanent.removeSummoningSickness();
+        permanent.setTapped(tapped);
+        PermanentView cardView = new PermanentView(permanent, permCard, controllerId, game);
 
         return cardView;
     }
 
     private CardView createFaceDownCard(Game game, UUID controllerId, String code, String cardNumber, boolean isMorphed, boolean isManifested, boolean tapped) {
-        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber);
+        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber, false);
         ExpansionInfo setInfo = ExpansionRepository.instance.getSetByCode(code);
         CardSetInfo testSet = new CardSetInfo(cardInfo.getName(), setInfo.getCode(), cardNumber, cardInfo.getRarity(),
                 new CardGraphicInfo(cardInfo.getFrameStyle(), cardInfo.usesVariousArt()));
@@ -170,7 +178,7 @@ public class TestCardRenderDialog extends MageDialog {
     }
 
     private CardView createHandCard(Game game, UUID controllerId, String code, String cardNumber) {
-        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber);
+        CardInfo cardInfo = CardRepository.instance.findCard(code, cardNumber, false);
         ExpansionInfo setInfo = ExpansionRepository.instance.getSetByCode(code);
         CardSetInfo testSet = new CardSetInfo(cardInfo.getName(), setInfo.getCode(), cardNumber, cardInfo.getRarity(),
                 new CardGraphicInfo(cardInfo.getFrameStyle(), cardInfo.usesVariousArt()));
@@ -303,12 +311,21 @@ public class TestCardRenderDialog extends MageDialog {
 
         //test split, transform and mdf in hands
         cardViews.add(createHandCard(game, playerYou.getId(), "SOI", "97")); // Accursed Witch
-        cardViews.add(createHandCard(game, playerYou.getId(), "UMA", "225")); // Fire // Ice
+        //cardViews.add(createHandCard(game, playerYou.getId(), "UMA", "225")); // Fire // Ice
-        cardViews.add(createHandCard(game, playerYou.getId(), "ELD", "14")); // Giant Killer
+        //cardViews.add(createHandCard(game, playerYou.getId(), "ELD", "14")); // Giant Killer
-        cardViews.add(createHandCard(game, playerYou.getId(), "ZNR", "134")); // Akoum Warrior
+        //cardViews.add(createHandCard(game, playerYou.getId(), "ZNR", "134")); // Akoum Warrior
         //*/
 
-        //* //test card icons
+        // test meld cards in hands and battlefield
+        cardViews.add(createHandCard(game, playerYou.getId(), "EMN", "204")); // Hanweir Battlements
+        cardViews.add(createHandCard(game, playerYou.getId(), "EMN", "130a")); // Hanweir Garrison
+        cardViews.add(createHandCard(game, playerYou.getId(), "EMN", "130b")); // Hanweir, the Writhing Township
+        cardViews.add(createPermanentCard(game, playerYou.getId(), "EMN", "204", 1, 1, 0, false, false, null)); // Hanweir Battlements
+        cardViews.add(createPermanentCard(game, playerYou.getId(), "EMN", "130a", 1, 1, 0, false, false, null)); // Hanweir Garrison
+        cardViews.add(createPermanentCard(game, playerYou.getId(), "EMN", "130b", 1, 1, 0, false, false, null)); // Hanweir, the Writhing Township
+        //*/
+
+        /* //test card icons
         cardViews.add(createHandCard(game, playerYou.getId(), "POR", "169")); // Grizzly Bears
         cardViews.add(createHandCard(game, playerYou.getId(), "DKA", "140")); // Huntmaster of the Fells, transforms
         cardViews.add(createPermanentCard(game, playerYou.getId(), "DKA", "140", 3, 3, 1, false, true, additionalIcons)); // Huntmaster of the Fells, transforms

Mage.Client/src/main/java/mage/client/plugins/adapters/MageActionCallback.java

@@ -672,7 +672,7 @@ public class MageActionCallback implements ActionCallback {
                     popupContainer.setVisible(true);
 
                     // popup hint mode
-                    Image image = null;
+                    Image image = cardPanel.getImage();
                     CardView displayCard = cardPanel.getOriginal();
                     switch (enlargeMode) {
                         case COPY:
@@ -696,12 +696,9 @@ public class MageActionCallback implements ActionCallback {
                         default:
                             break;
                     }
-                    if (image == null) {
+
-                        image = cardPanel.getImage();
-                    }
                     // shows the card in the popup Container
                     displayCardInfo(displayCard, image, (BigCard) cardPreviewPane);
-
                 } else {
                     logger.warn("No Card preview Pane in Mage Frame defined. Card: " + cardView.getName());
                 }

Mage.Client/src/main/java/org/mage/card/arcane/CardPanel.java

@@ -856,7 +856,7 @@ public abstract class CardPanel extends MagePermanent implements ComponentListen
         if (this.guiTransformed) {
             // main side -> alternative side
             if (this.cardSideOther == null) {
-                logger.error("no second side for card to transform!");
+                logger.error("can't find second side to toggle transform from main to second: " + this.getCard().getName());
                 return;
             }
             copySelections(this.cardSideMain, this.cardSideOther);
@@ -864,6 +864,10 @@ public abstract class CardPanel extends MagePermanent implements ComponentListen
             this.getGameCard().setAlternateName(this.cardSideMain.getName());
         } else {
             // alternative side -> main side
+            if (this.cardSideOther == null) {
+                logger.error("can't find second side to toggle transform from second side to main: " + this.getCard().getName());
+                return;
+            }
             copySelections(this.cardSideOther, this.cardSideMain);
             update(this.cardSideMain);
             this.getGameCard().setAlternateName(this.cardSideOther.getName());
@@ -945,10 +949,16 @@ public abstract class CardPanel extends MagePermanent implements ComponentListen
             }
         }
 
-        // fix other side: if it's a night side permanent then the main side info must be extracted
+        // fix other side: if it's a night side permanent then the main side info can be extracted from original
         if (this.cardSideOther == null || this.cardSideOther.getName().equals(this.cardSideMain.getName())) {
-            if (this.cardSideMain instanceof PermanentView) {
+            if ((this.cardSideMain instanceof PermanentView)) {
-                this.cardSideOther = ((PermanentView) this.cardSideMain).getOriginal();
+                // some "transformed" cards don't have info about main side
+                // (example: melded card have two main sides/cards),
+                // so it must be ignored until multiple hints implement like mtga
+                CardView original = ((PermanentView) this.cardSideMain).getOriginal();
+                if (original != null && !original.getName().equals(this.getName())) {
+                    this.cardSideOther = original;
+                }
             }
         }
     }

Mage.Client/src/main/java/org/mage/plugins/card/images/DownloadPicturesService.java

@@ -449,7 +449,8 @@ public class DownloadPicturesService extends DefaultBoundedRangeModel implements
                     // main side
                     allCardsUrls.add(url);
 
-                    // second side (xmage's set doesn't have info about it, so generate it here)
+                    // second side
+                    // xmage doesn't search night cards by default, so add it and other types manually
                     if (card.isDoubleFaced()) {
                         if (card.getSecondSideName() == null || card.getSecondSideName().trim().isEmpty()) {
                             throw new IllegalStateException("Second side card can't have empty name.");
@@ -460,7 +461,12 @@ public class DownloadPicturesService extends DefaultBoundedRangeModel implements
                             throw new IllegalStateException("Can''t find second side card in database: " + card.getSecondSideName());
                         }
 
-                        url = new CardDownloadData(card.getSecondSideName(), card.getSetCode(), secondSideCard.getCardNumber(), card.usesVariousArt(), 0, "", "", false, card.isDoubleFaced(), true);
+                        url = new CardDownloadData(
+                                card.getSecondSideName(),
+                                card.getSetCode(),
+                                secondSideCard.getCardNumber(),
+                                card.usesVariousArt(),
+                                0, "", "", false, card.isDoubleFaced(), true);
                         url.setType2(isType2);
                         allCardsUrls.add(url);
                     }
@@ -479,6 +485,26 @@ public class DownloadPicturesService extends DefaultBoundedRangeModel implements
                         cardDownloadData.setType2(isType2);
                         allCardsUrls.add(cardDownloadData);
                     }
+                    if (card.getMeldsToCardName() != null) {
+                        if (card.getMeldsToCardName().trim().isEmpty()) {
+                            throw new IllegalStateException("MeldsToCardName can't be empty in " + card.getName());
+                        }
+
+                        CardInfo meldsToCard = CardRepository.instance.findCardWPreferredSet(card.getMeldsToCardName(), card.getSetCode());
+                        if (meldsToCard == null) {
+                            throw new IllegalStateException("Can''t find meldsToCard in database: " + card.getMeldsToCardName());
+                        }
+
+                        // meld cards are normal cards from the set, so no needs to set two faces/sides here
+                        url = new CardDownloadData(
+                                card.getMeldsToCardName(),
+                                card.getSetCode(),
+                                meldsToCard.getCardNumber(),
+                                card.usesVariousArt(),
+                                0, "", "", false, false, false);
+                        url.setType2(isType2);
+                        allCardsUrls.add(url);
+                    }
                     if (card.isModalDoubleFacesCard()) {
                         if (card.getModalDoubleFacesSecondSideName() == null || card.getModalDoubleFacesSecondSideName().trim().isEmpty()) {
                             throw new IllegalStateException("MDF card can't have empty name.");

Mage.Common/src/main/java/mage/view/CardView.java

@@ -519,6 +519,13 @@ public class CardView extends SimpleCardView {
             this.alternateName = mdfCard.getRightHalfCard().getName();
         }
 
+        Card meldsToCard = card.getMeldsToCard();
+        if (meldsToCard != null) {
+            this.transformable = true; // enable GUI day/night button
+            this.secondCardFace = new CardView(meldsToCard, game);
+            this.alternateName = meldsToCard.getName();
+        }
+
         if (card instanceof Spell) {
             this.mageObjectType = MageObjectType.SPELL;
             Spell spell = (Spell) card;

Mage.Sets/src/mage/cards/a/ArgothSanctumOfNature.java

@@ -47,6 +47,7 @@ public final class ArgothSanctumOfNature extends CardImpl {
         super(ownerId, setInfo, new CardType[]{CardType.LAND}, "");
 
         this.meldsWithClazz = mage.cards.t.TitaniaVoiceOfGaea.class;
+        this.meldsToClazz = mage.cards.h.HanweirTheWrithingTownship.class;
 
         // Argoth, Sanctum of Nature enters the battlefield tapped unless you control a legendary green creature.
         this.addAbility(new EntersBattlefieldAbility(

Mage.Sets/src/mage/cards/b/BrunaTheFadingLight.java

@@ -42,7 +42,9 @@ public final class BrunaTheFadingLight extends CardImpl {
         this.subtype.add(SubType.ANGEL, SubType.HORROR);
         this.power = new MageInt(5);
         this.toughness = new MageInt(7);
+
         this.meldsWithClazz = mage.cards.g.GiselaTheBrokenBlade.class;
+        this.meldsToClazz = mage.cards.b.BriselaVoiceOfNightmares.class;
 
         // When you cast Bruna, the Fading Light, you may return target Angel or Human creature card from your graveyard to the battlefield.
         Effect effect = new ReturnFromGraveyardToBattlefieldTargetEffect();

Mage.Sets/src/mage/cards/g/GarrukRelentless.java

@@ -30,7 +30,7 @@ public final class GarrukRelentless extends CardImpl {
         this.addSuperType(SuperType.LEGENDARY);
         this.subtype.add(SubType.GARRUK);
 
-        this.secondSideCardClazz = GarrukTheVeilCursed.class;
+        this.secondSideCardClazz = mage.cards.g.GarrukTheVeilCursed.class;
 
         this.setStartingLoyalty(3);
 

Mage.Sets/src/mage/cards/g/GatstafArsonists.java

@@ -22,7 +22,7 @@ public final class GatstafArsonists extends CardImpl {
         this.power = new MageInt(5);
         this.toughness = new MageInt(4);
 
-        this.secondSideCardClazz = GatstafRavagers.class;
+        this.secondSideCardClazz = mage.cards.g.GatstafRavagers.class;
 
         // At the beginning of each upkeep, if no spells were cast last turn, transform Gatstaf Arsonists.
         this.addAbility(new TransformAbility());

Mage.Sets/src/mage/cards/g/GatstafShepherd.java

@@ -20,7 +20,7 @@ public final class GatstafShepherd extends CardImpl {
         this.subtype.add(SubType.HUMAN);
         this.subtype.add(SubType.WEREWOLF);
 
-        this.secondSideCardClazz = GatstafHowler.class;
+        this.secondSideCardClazz = mage.cards.g.GatstafHowler.class;
 
         this.power = new MageInt(2);
         this.toughness = new MageInt(2);

Mage.Sets/src/mage/cards/g/GiselaTheBrokenBlade.java

@@ -31,7 +31,9 @@ public final class GiselaTheBrokenBlade extends CardImpl {
         this.subtype.add(SubType.HORROR);
         this.power = new MageInt(4);
         this.toughness = new MageInt(3);
+
         this.meldsWithClazz = mage.cards.b.BrunaTheFadingLight.class;
+        this.meldsToClazz = mage.cards.b.BriselaVoiceOfNightmares.class;
 
         // Flying
         this.addAbility(FlyingAbility.getInstance());

Mage.Sets/src/mage/cards/g/GrafRats.java

@@ -26,7 +26,9 @@ public final class GrafRats extends CardImpl {
         this.subtype.add(SubType.RAT);
         this.power = new MageInt(2);
         this.toughness = new MageInt(1);
+
         this.meldsWithClazz = mage.cards.m.MidnightScavengers.class;
+        this.meldsToClazz = mage.cards.c.ChitteringHost.class;
 
         // At the beginning of combat on your turn, if you both own and control Graf Rats and a creature named Midnight Scavengers, exile them, then meld them into Chittering Host.
         this.addAbility(new ConditionalInterveningIfTriggeredAbility(

Mage.Sets/src/mage/cards/g/GrimlockDinobotLeader.java

@@ -47,7 +47,7 @@ public final class GrimlockDinobotLeader extends CardImpl{
         this.power = new MageInt(4);
         this.toughness = new MageInt(4);
 
-        this.secondSideCardClazz = GrimlockFerociousKing.class;
+        this.secondSideCardClazz = mage.cards.g.GrimlockFerociousKing.class;
 
         // Dinosaurs, Vehicles and other Transformers creatures you control get +2/+0.
         this.addAbility(new SimpleStaticAbility(Zone.BATTLEFIELD, new BoostControlledEffect(2, 0, Duration.WhileOnBattlefield, filter, false)));

Mage.Sets/src/mage/cards/g/GrizzledAngler.java

@@ -32,7 +32,7 @@ public final class GrizzledAngler extends CardImpl {
         this.power = new MageInt(2);
         this.toughness = new MageInt(3);
 
-        this.secondSideCardClazz = GrislyAnglerfish.class;
+        this.secondSideCardClazz = mage.cards.g.GrislyAnglerfish.class;
 
         // {T}: Put the top two cards of your library into your graveyard. Then if there is a colorless creature card in your graveyard, transform Grizzled Angler.
         this.addAbility(new TransformAbility());

Mage.Sets/src/mage/cards/h/HanweirBattlements.java

@@ -29,7 +29,9 @@ public final class HanweirBattlements extends CardImpl {
 
     public HanweirBattlements(UUID ownerId, CardSetInfo setInfo) {
         super(ownerId, setInfo, new CardType[]{CardType.LAND}, "");
+
         this.meldsWithClazz = mage.cards.h.HanweirGarrison.class;
+        this.meldsToClazz = mage.cards.h.HanweirTheWrithingTownship.class;
 
         // {T}: Add {C}.
         this.addAbility(new ColorlessManaAbility());

Mage.Sets/src/mage/cards/h/HanweirGarrison.java

@@ -26,7 +26,9 @@ public final class HanweirGarrison extends CardImpl {
         this.subtype.add(SubType.SOLDIER);
         this.power = new MageInt(2);
         this.toughness = new MageInt(3);
+
         this.meldsWithClazz = mage.cards.h.HanweirBattlements.class;
+        this.meldsToClazz = mage.cards.h.HanweirTheWrithingTownship.class;
 
         // Whenever Hanweir Garrison attacks, create two 1/1 red Human creature tokens tapped and attacking.
         this.addAbility(new AttacksTriggeredAbility(new CreateTokenEffect(new RedHumanToken(), 2, true, true), false));

Mage.Sets/src/mage/cards/h/HinterlandHermit.java

@@ -20,7 +20,7 @@ public final class HinterlandHermit extends CardImpl {
         this.subtype.add(SubType.HUMAN);
         this.subtype.add(SubType.WEREWOLF);
 
-        this.secondSideCardClazz = HinterlandScourge.class;
+        this.secondSideCardClazz = mage.cards.h.HinterlandScourge.class;
 
         this.power = new MageInt(2);
         this.toughness = new MageInt(1);

Mage.Sets/src/mage/cards/m/MidnightScavengers.java

@@ -37,7 +37,9 @@ public final class MidnightScavengers extends CardImpl {
         this.subtype.add(SubType.ROGUE);
         this.power = new MageInt(3);
         this.toughness = new MageInt(3);
+
         this.meldsWithClazz = mage.cards.g.GrafRats.class;
+        this.meldsToClazz = mage.cards.c.ChitteringHost.class;
 
         // When Midnight Scavengers enters the battlefield, you may return target creature card with converted mana cost 3 or less from your graveyard to your hand.
         Ability ability = new EntersBattlefieldTriggeredAbility(new ReturnFromGraveyardToHandTargetEffect(), true);

Mage.Sets/src/mage/cards/m/MishraClaimedByGix.java

@@ -38,7 +38,9 @@ public final class MishraClaimedByGix extends CardImpl {
         this.subtype.add(SubType.ARTIFICER);
         this.power = new MageInt(3);
         this.toughness = new MageInt(5);
+
         this.meldsWithClazz = mage.cards.p.PhyrexianDragonEngine.class;
+        this.meldsToClazz = mage.cards.m.MishraLostToPhyrexia.class;
 
         // Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters the battlefield tapped and attacking.
         Ability ability = new AttacksWithCreaturesTriggeredAbility(

Mage.Sets/src/mage/cards/p/PhyrexianDragonEngine.java

@@ -31,7 +31,9 @@ public final class PhyrexianDragonEngine extends CardImpl {
         this.subtype.add(SubType.DRAGON);
         this.power = new MageInt(2);
         this.toughness = new MageInt(2);
+
         this.meldsWithClazz = mage.cards.m.MishraClaimedByGix.class;
+        this.meldsToClazz = mage.cards.m.MishraLostToPhyrexia.class;
 
         // Double strike
         this.addAbility(DoubleStrikeAbility.getInstance());

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

@@ -31,6 +31,7 @@ public final class TheMightstoneAndWeakstone extends CardImpl {
         this.subtype.add(SubType.POWERSTONE);
 
         this.meldsWithClazz = mage.cards.u.UrzaLordProtector.class;
+        this.meldsToClazz = mage.cards.u.UrzaPlaneswalker.class;
 
         // When The Mightstone and Weakstone enters the battlefield, choose one --
         // * Draw two cards.

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

@@ -39,7 +39,9 @@ public final class TitaniaVoiceOfGaea extends CardImpl {
         this.subtype.add(SubType.ELEMENTAL);
         this.power = new MageInt(3);
         this.toughness = new MageInt(4);
+
         this.meldsWithClazz = mage.cards.a.ArgothSanctumOfNature.class;
+        this.meldsToClazz = mage.cards.t.TitaniaGaeaIncarnate.class;
 
         // Reach
         this.addAbility(ReachAbility.getInstance());

Mage.Sets/src/mage/cards/u/UrzaLordProtector.java

@@ -46,7 +46,9 @@ public final class UrzaLordProtector extends CardImpl {
         this.subtype.add(SubType.ARTIFICER);
         this.power = new MageInt(2);
         this.toughness = new MageInt(4);
+
         this.meldsWithClazz = mage.cards.t.TheMightstoneAndWeakstone.class;
+        this.meldsToClazz = mage.cards.u.UrzaPlaneswalker.class;
 
         // Artifact, instant, and sorcery spells you cast cost {1} less to cast.
         this.addAbility(new SimpleStaticAbility(new SpellsCostReductionControllerEffect(filter, 1)));

Mage/src/main/java/mage/cards/Card.java

@@ -80,6 +80,14 @@ public interface Card extends MageObject {
         return false;
     }
 
+    default Class<? extends Card> getMeldsToClazz() {
+        return null;
+    }
+
+    default Card getMeldsToCard() {
+        return null;
+    }
+
     void assignNewId();
 
     void addInfo(String key, String value, Game game);

Mage/src/main/java/mage/cards/CardImpl.java

@@ -47,6 +47,8 @@ public abstract class CardImpl extends MageObjectImpl implements Card {
     protected Rarity rarity;
     protected Class<? extends Card> secondSideCardClazz;
     protected Class<? extends Card> meldsWithClazz;
+    protected Class<? extends Card> meldsToClazz;
+    protected Card meldsToCard;
     protected Card secondSideCard;
     protected boolean nightCard;
     protected SpellAbility spellAbility;
@@ -127,6 +129,8 @@ public abstract class CardImpl extends MageObjectImpl implements Card {
         secondSideCard = null; // will be set on first getSecondCardFace call if card has one
         nightCard = card.nightCard;
         meldsWithClazz = card.meldsWithClazz;
+        meldsToClazz = card.meldsToClazz;
+        meldsToCard = null; // will be set on first getMeldsToCard call if card has one
 
         spellAbility = null; // will be set on first getSpellAbility call if card has one
         flipCard = card.flipCard;
@@ -614,29 +618,36 @@ public abstract class CardImpl extends MageObjectImpl implements Card {
 
     @Override
     public boolean isTransformable() {
+        // warning, not all multifaces cards can be transformable (meld, mdfc)
+        // mtg rules method: here
+        // GUI related method: search "transformable = true" in CardView
+        // TODO: check and fix method usage in game engine, it's must be mtg rules logic, not GUI
         return this.secondSideCardClazz != null || this.nightCard;
     }
 
     @Override
     public final Card getSecondCardFace() {
-        // init second side card on first call
+        // init card side on first call
         if (secondSideCardClazz == null && secondSideCard == null) {
             return null;
         }
 
-        if (secondSideCard != null) {
+        if (secondSideCard == null) {
-            return secondSideCard;
+            secondSideCard = initSecondSideCard(secondSideCardClazz);
         }
 
+        return secondSideCard;
+    }
+
+    private Card initSecondSideCard(Class<? extends Card> cardClazz) {
         // must be non strict search in any sets, not one set
         // example: if set contains only one card side
         // method used in cards database creating, so can't use repository here
-        ExpansionSet.SetCardInfo info = Sets.findCardByClass(secondSideCardClazz, expansionSetCode);
+        ExpansionSet.SetCardInfo info = Sets.findCardByClass(cardClazz, expansionSetCode);
         if (info == null) {
             return null;
         }
-        secondSideCard = createCard(secondSideCardClazz, new CardSetInfo(info.getName(), expansionSetCode, info.getCardNumber(), info.getRarity(), info.getGraphicInfo()));
+        return createCard(cardClazz, new CardSetInfo(info.getName(), expansionSetCode, info.getCardNumber(), info.getRarity(), info.getGraphicInfo()));
-        return secondSideCard;
     }
 
     @Override
@@ -653,6 +664,25 @@ public abstract class CardImpl extends MageObjectImpl implements Card {
         return this.meldsWithClazz != null && this.meldsWithClazz.isInstance(card.getMainCard());
     }
 
+    @Override
+    public Class<? extends Card> getMeldsToClazz() {
+        return this.meldsToClazz;
+    }
+
+    @Override
+    public Card getMeldsToCard() {
+        // init card on first call
+        if (meldsToClazz == null && meldsToCard == null) {
+            return null;
+        }
+
+        if (meldsToCard == null) {
+            meldsToCard = initSecondSideCard(meldsToClazz);
+        }
+
+        return meldsToCard;
+    }
+
     @Override
     public boolean isNightCard() {
         return this.nightCard;

Mage/src/main/java/mage/cards/MeldCard.java

@@ -109,6 +109,8 @@ public abstract class MeldCard extends CardImpl {
 
     @Override
     public boolean isTransformable() {
+        // there are multiple day cards for one meld card, so can't show it as second side
+        // TODO: can be fixed after mutiple sides implement, e.g. with Mutate support
         return false;
     }
 

Mage/src/main/java/mage/cards/repository/CardInfo.java

@@ -93,7 +93,7 @@ public class CardInfo {
     protected boolean flipCard;
     @DatabaseField
     protected boolean doubleFaced;
-    @DatabaseField(indexName = "name_index")
+    @DatabaseField(indexName = "nightCard_index")
     protected boolean nightCard;
     @DatabaseField
     protected String flipCardName;
@@ -107,6 +107,8 @@ public class CardInfo {
     protected boolean modalDoubleFacesCard;
     @DatabaseField
     protected String modalDoubleFacesSecondSideName;
+    @DatabaseField
+    protected String meldsToCardName;
 
     // if you add new field with card side name then update CardRepository.addNewNames too
 
@@ -134,6 +136,11 @@ public class CardInfo {
         this.flipCard = card.isFlipCard();
         this.flipCardName = card.getFlipCardName();
 
+        Card meldToCard = card.getMeldsToCard();
+        if (meldToCard != null) {
+            this.meldsToCardName = meldToCard.getName();
+        }
+
         this.doubleFaced = card.isTransformable() && card.getSecondCardFace() != null;
         this.nightCard = card.isNightCard();
         Card secondSide = card.getSecondCardFace();
@@ -437,6 +444,10 @@ public class CardInfo {
         return flipCardName;
     }
 
+    public String getMeldsToCardName() {
+        return meldsToCardName;
+    }
+
     public boolean isDoubleFaced() {
         return doubleFaced;
     }

Mage/src/main/java/mage/cards/repository/CardRepository.java

@@ -117,6 +117,9 @@ public enum CardRepository {
         if (card.getFlipCardName() != null && !card.getFlipCardName().isEmpty()) {
             namesList.add(card.getFlipCardName());
         }
+        if (card.getMeldsToCardName() != null && !card.getMeldsToCardName().isEmpty()) {
+            namesList.add(card.getMeldsToCardName());
+        }
     }
 
     public static Boolean haveSnowLands(String setCode) {
@@ -528,6 +531,8 @@ public enum CardRepository {
      * Warning, don't use db functions in card's code - it generates heavy db loading in AI simulations. If you
      * need that feature then check for simulation mode. See https://github.com/magefree/mage/issues/7014
      *
+     * Ignoring night cards by default
+     *
      * @param criteria
      * @return
      */

Mage/src/main/java/mage/game/permanent/PermanentCard.java

@@ -71,7 +71,7 @@ public class PermanentCard extends PermanentImpl {
         if (card instanceof LevelerCard) {
             maxLevelCounters = ((LevelerCard) card).getMaxLevelCounters();
         }
-        if (isTransformable()) {
+        if (card.isTransformable()) {
             if (game.getState().getValue(TransformAbility.VALUE_KEY_ENTER_TRANSFORMED + getId()) != null
                     || NightboundAbility.checkCard(this, game)) {
                 game.getState().setValue(TransformAbility.VALUE_KEY_ENTER_TRANSFORMED + getId(), null);
@@ -133,6 +133,9 @@ public class PermanentCard extends PermanentImpl {
         if (card.getSecondCardFace() != null) {
             this.secondSideCardClazz = card.getSecondCardFace().getClass();
         }
+        if (card.getMeldsToCard() != null) {
+            this.meldsToClazz = card.getMeldsToCard().getClass();
+        }
         this.nightCard = card.isNightCard();
         this.flipCard = card.isFlipCard();
         this.flipCardName = card.getFlipCardName();