Try to keep original card and not migrate to new card

forge-game/src/main/java/forge/game/GameAction.java

@@ -338,13 +338,10 @@ public class GameAction {
         }
 
         // update state for view
-        copied.updateStateForView();
         if (copied.isMerged()) {
-            if (copied.getMergedToCard() != null) {
             copied.getMergedToCard().updateStateForView();
         } else {
-                copied.getMergedCards().get(0).updateStateForView();
+            copied.updateStateForView();
-            }
         }
 
         if (fromBattlefield) {

forge-game/src/main/java/forge/game/ability/effects/MutateEffect.java

@@ -47,17 +47,17 @@ public class MutateEffect extends SpellAbilityEffect {
         );
         final boolean putOnTop = (topCard == host);
 
+        host.setMergedToCard(target);
+        // If first time mutate, add target first.
+        if (target.getMergedCards().isEmpty()) {
+            target.addMergedCard(target);
+        }
         if (putOnTop) {
-            host.addMergedCard(target);
+            target.addMergedCardToTop(host);
-            host.addMergedCards(target.getMergedCards());
-            target.clearMergedCards();
-            target.setMergedToCard(host);
         } else {
             target.addMergedCard(host);
-            host.setMergedToCard(target);
         }
 
-
         // First remove current mutated states
         if (target.getMutatedTimestamp() != -1) {
             target.removeCloneState(target.getMutatedTimestamp());
@@ -66,27 +66,21 @@ public class MutateEffect extends SpellAbilityEffect {
         // Now add all abilities from bottom cards
         final Long ts = game.getNextTimestamp();
         if (topCard.getCurrentStateName() != CardStateName.FaceDown) {
-            final CardCloneStates mutatedStates = CardFactory.getMutatedCloneStates(topCard, sa);
+            final CardCloneStates mutatedStates = CardFactory.getMutatedCloneStates(target, sa);
-            topCard.addCloneState(mutatedStates, ts);
+            target.addCloneState(mutatedStates, ts);
-            topCard.setMutatedTimestamp(ts);
+            target.setMutatedTimestamp(ts);
         }
-        if (topCard == target) {
         // Re-register triggers for target card
         game.getTriggerHandler().clearActiveTriggers(target, null);
         game.getTriggerHandler().registerActiveTrigger(target, false);
-        }
 
         game.getAction().moveToPlay(host, p, sa);
 
-        if (topCard == host) {
-            CardFactory.migrateTopCard(host, target);
-        } else {
         host.setTapped(target.isTapped());
         host.setFlipped(target.isFlipped());
-        }
+        target.setTimesMutated(target.getTimesMutated() + 1);
-        topCard.setTimesMutated(topCard.getTimesMutated() + 1);
 
-        game.getTriggerHandler().runTrigger(TriggerType.Mutates, AbilityKey.mapFromCard(topCard), false);
+        game.getTriggerHandler().runTrigger(TriggerType.Mutates, AbilityKey.mapFromCard(target), false);
     }
 
 }

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

@@ -1010,8 +1010,9 @@ public class Card extends GameEntity implements Comparable<Card>, IHasSVars {
     public final void addMergedCard(final Card c) {
         mergedCards = view.addCard(mergedCards, c, TrackableProperty.MergedCards);
     }
-    public final void addMergedCards(final Iterable<Card> cards) {
+    public final void addMergedCardToTop(final Card c) {
-        mergedCards = view.addCards(mergedCards, cards, TrackableProperty.MergedCards);
+        mergedCards.add(0, c);
+        view.setCards(mergedCards, mergedCards, TrackableProperty.MergedCards);
     }
     public final void removeMergedCard(final Card c) {
         mergedCards = view.removeCard(mergedCards, c, TrackableProperty.MergedCards);
@@ -1028,7 +1029,7 @@ public class Card extends GameEntity implements Comparable<Card>, IHasSVars {
     }
 
     public final boolean isMerged() {
-        return !getMergedCards().isEmpty() || getMergedToCard() != null;
+        return getMergedToCard() != null;
     }
 
     public final boolean isMutated() {
@@ -3740,9 +3741,6 @@ public class Card extends GameEntity implements Comparable<Card>, IHasSVars {
         if (tapped == tapped0) { return; }
         tapped = tapped0;
         view.updateTapped(this);
-        for (final Card c : getMergedCards()) {
-            c.setTapped(tapped0);
-        }
     }
 
     public final void tap() {

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

@@ -823,49 +823,23 @@ public class CardFactory {
     }
 
     public static CardCloneStates getMutatedCloneStates(final Card card, final CardTraitBase sa) {
-        final CardStateName state = card.getCurrentStateName();
+        final Card top = card.getMergedCards().get(0);
+        final CardStateName state = top.getCurrentStateName();
         final CardState ret = new CardState(card, state);
-        ret.copyFrom(card.getState(state, true), false);
+        ret.copyFrom(top.getState(state, true), false);
 
+        boolean first = true;
         for (final Card c : card.getMergedCards()) {
+            if (first) {
+                first = false;
+                continue;
+            }
             ret.addAbilitiesFrom(c.getCurrentState(), false);
         }
 
-        final CardCloneStates result = new CardCloneStates(card, sa);
+        final CardCloneStates result = new CardCloneStates(top, sa);
         result.put(state, ret);
         return result;
     }
 
-    public static void migrateTopCard(final Card host, final Card target) {
-        // Copy all status from target card and migrate all counters
-        // Also update all reference of target card to new top card
-
-        // TODO: find out all necessary status that should be copied
-        host.setTapped(target.isTapped());
-        host.setSickness(target.isFirstTurnControlled());
-        host.setFlipped(target.isFlipped());
-        host.setDamage(target.getDamage());
-        host.setTimesMutated(target.getTimesMutated());
-        host.setMonstrous(target.isMonstrous());
-        host.setRenowned(target.isRenowned());
-
-        // Migrate counters
-        Map<CounterType, Integer> counters = target.getCounters();
-        if (!counters.isEmpty()) {
-            host.setCounters(Maps.newHashMap(counters));
-        }
-        target.clearCounters();
-
-        // Migrate attached cards
-        CardCollectionView attached = target.getAttachedCards();
-        for (final Card c : attached) {
-            c.setEntityAttachedTo(host);
-        }
-        target.setAttachedCards(null);
-        host.setAttachedCards(attached);
-
-        // TODO: move all remembered, imprinted objects to new top card
-        //       and possibly many other needs to be migrated.
-    }
-
 } // end class AbstractCardFactory

forge-game/src/main/java/forge/game/player/PlayerView.java

@@ -470,7 +470,7 @@ public class PlayerView extends GameEntityView {
     void updateZone(PlayerZone zone) {
         TrackableProperty prop = getZoneProp(zone.getZoneType());
         if (prop == null) { return; }
-        set(prop, CardView.getCollection(zone.getCards(false, false)));
+        set(prop, CardView.getCollection(zone.getCards(false, true)));
 
         //update delirium
         if (ZoneType.Graveyard == zone.getZoneType())

forge-gui-desktop/src/main/java/forge/view/arcane/PlayArea.java

@@ -685,21 +685,6 @@ public class PlayArea extends CardPanelContainer implements CardPanelMouseListen
         }
         toPanel.getAttachedPanels().clear();
 
-        // Treat merged cards like attached cards
-        if (card.hasMergedCards()) {
-            final Iterable<CardView> merged = card.getMergedCards();
-            for (final CardView c : merged) {
-                final CardPanel cardC = getCardPanel(c.getId());
-                if (cardC != null) {
-                    if (cardC.getAttachedToPanel() != toPanel) {
-                        cardC.setAttachedToPanel(toPanel);
-                        needLayoutRefresh = true; //ensure layout refreshed if any attachments change
-                    }
-                    toPanel.getAttachedPanels().add(cardC);
-                }
-            }
-        }
-
         if (card.hasCardAttachments()) {
             final Iterable<CardView> enchants = card.getAttachedCards();
             for (final CardView e : enchants) {
@@ -714,13 +699,11 @@ public class PlayArea extends CardPanelContainer implements CardPanelMouseListen
             }
         }
 
-        // Treat merged cards like attached cards
         CardPanel attachedToPanel;
-        if (card.getMergedTo() != null) {
+        if (card.getAttachedTo() != null) {
-            attachedToPanel = getCardPanel(card.getMergedTo().getId());
-        } else if (card.getAttachedTo() != null) {
             attachedToPanel = getCardPanel(card.getAttachedTo().getId());
-        } else {
+        }
+        else {
             attachedToPanel = null;
         }
         if (toPanel.getAttachedToPanel() != attachedToPanel) {

forge-gui-mobile/src/forge/screens/match/views/VCardDisplayArea.java

@@ -286,17 +286,6 @@ public abstract class VCardDisplayArea extends VDisplayArea implements ActivateH
 
             attachedPanels.clear();
 
-            // Treat merged cards like attached cards
-            if (card.hasMergedCards()) {
-                final Iterable<CardView> merged = card.getMergedCards();
-                for (final CardView c : merged) {
-                    final CardAreaPanel cardC = CardAreaPanel.get(c);
-                    if (cardC != null) {
-                        attachedPanels.add(cardC);
-                    }
-                }
-            }
-
             if (card.hasCardAttachments()) {
                 final Iterable<CardView> enchants = card.getAttachedCards();
                 for (final CardView e : enchants) {
@@ -307,10 +296,7 @@ public abstract class VCardDisplayArea extends VDisplayArea implements ActivateH
                 }
             }
        
-            if (card.getMergedTo() != null ) {
+            if (card.getAttachedTo() != null) {
-                setAttachedToPanel(CardAreaPanel.get(card.getMergedTo()));
-            }
-            else if (card.getAttachedTo() != null) {
                 setAttachedToPanel(CardAreaPanel.get(card.getAttachedTo()));
             }
             else {

forge-gui/res/cardsfolder/p/pollywog_symbiote.txt

@@ -0,0 +1,10 @@
+Name:Pollywog Symbiote
+ManaCost:1 U
+Types:Creature Frog
+PT:1/3
+S:Mode$ ReduceCost | ValidCard$ Creature.withMutate | Type$ Spell | Activator$ You | Amount$ 1 | Description$ Each creature spell you cast costs {1} less to cast if it has mutate.
+T:Mode$ SpellCast | ValidCard$ Creature.withMutate | ValidActivatingPlayer$ You | Execute$ TrigLoot | TriggerZones$ Battlefield | TriggerDescription$ Whenever you cast a creature spell, if it has mutate, draw a card, then discard a card.
+SVar:TrigLoot:DB$ Draw | Defined$ You | NumCards$ 1 | SubAbility$ DBDiscard
+SVar:DBDiscard:DB$ Discard | Defined$ You | NumCards$ 1 | Mode$ TgtChoose
+SVar:BuffedBy:Card.withMutate
+Oracle:Each creature spell you cast costs {1} less to cast if it has mutate.\nWhenever you cast a creature spell, if it has mutate, draw a card, then discard a card.