- Rule 800.4: When a player leaves a multiplayer game, removing objects associated with that Player from the game.

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

@@ -573,6 +573,23 @@ public class Game {
     }
 
     public void onPlayerLost(Player p) {
+        // Rule 800.4 Losing a Multiplayer game
+        CardCollectionView cards = this.getCardsInGame();
+
+        for(Card c : cards) {
+            if (c.getOwner().equals(p)) {
+                c.ceaseToExist();
+            } else {
+                c.removeTempController(p);
+                if (c.getController().equals(p)) {
+                    this.getAction().exile(c);
+                }
+            }
+        }
+
+        // Remove leftover items from
+        this.getStack().removeInstancesControlledBy(p);
+
         ingamePlayers.remove(p);
 
         final Map<String, Object> runParams = new TreeMap<String, Object>();

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

@@ -2201,6 +2201,15 @@ public class Card extends GameEntity implements Comparable<Card> {
         }
     }
 
+    public final void removeTempController(final Player player) {
+        // Remove each key that yields this player
+        for(Entry<Long,Player> kv : tempControllers.entrySet()) {
+            if (kv.getValue().equals(player)) {
+                tempControllers.remove(kv.getKey());
+            }
+        }
+    }
+
     public final void clearTempControllers() {
         if (tempControllers.isEmpty()) { return; }
         tempControllers.clear();
@@ -3436,9 +3445,7 @@ public class Card extends GameEntity implements Comparable<Card> {
 
             // Just remove it's zone, so we don't run through the exile stuff
             // This allows auras on phased out tokens to just phase out permanently
-            getGame().getTriggerHandler().suppressMode(TriggerType.ChangesZone);
-            getZone().remove(this);
-            getGame().getTriggerHandler().clearSuppression(TriggerType.ChangesZone);
+            this.ceaseToExist();
         }
 
         if (!phasedOut) {
@@ -6710,4 +6717,10 @@ public class Card extends GameEntity implements Comparable<Card> {
             this.changedCardColors.put(entry.getKey(), entry.getValue());
         }
     }
+
+    public void ceaseToExist() {
+        getGame().getTriggerHandler().suppressMode(TriggerType.ChangesZone);
+        getZone().remove(this);
+        getGame().getTriggerHandler().clearSuppression(TriggerType.ChangesZone);
+    }
 }

forge-game/src/main/java/forge/game/zone/MagicStack.java

@@ -719,6 +719,14 @@ public class MagicStack /* extends MyObservable */ implements Iterable<SpellAbil
         }
     }
 
+    public final void removeInstancesControlledBy(final Player p) {
+        for (SpellAbilityStackInstance si : stack) {
+            if (si.getActivatingPlayer().equals(p)) {
+                remove(si);
+            }
+        }
+    }
+
     public void fizzleTriggersOnStackTargeting(Card c, TriggerType t) {
         for (SpellAbilityStackInstance si : stack) {
             SpellAbility sa = si.getSpellAbility(false);