[OTJ] Implement Rambling Possum

Mage/src/main/java/mage/constants/SubType.java

@@ -316,6 +316,7 @@ public enum SubType {
     PIRATE("Pirate", SubTypeSet.CreatureType),
     PLANT("Plant", SubTypeSet.CreatureType),
     PORCUPINE("Porcupine", SubTypeSet.CreatureType),
+    POSSUM("Possum", SubTypeSet.CreatureType),
     PRAETOR("Praetor", SubTypeSet.CreatureType),
     PRIMARCH("Primarch", SubTypeSet.CreatureType),
     PRISM("Prism", SubTypeSet.CreatureType),

Mage/src/main/java/mage/filter/predicate/permanent/SaddledSourceThisTurnPredicate.java

@@ -0,0 +1,26 @@
+package mage.filter.predicate.permanent;
+
+import mage.filter.predicate.ObjectSourcePlayer;
+import mage.filter.predicate.ObjectSourcePlayerPredicate;
+import mage.game.Game;
+import mage.game.permanent.Permanent;
+import mage.watchers.common.SaddledMountWatcher;
+
+/**
+ * @author TheElk801
+ */
+public enum SaddledSourceThisTurnPredicate implements ObjectSourcePlayerPredicate<Permanent> {
+    instance;
+
+    @Override
+    public boolean apply(ObjectSourcePlayer<Permanent> input, Game game) {
+        return SaddledMountWatcher.checkIfSaddledThisTurn(
+                input.getObject(), input.getSource().getSourcePermanentOrLKI(game), game
+        );
+    }
+
+    @Override
+    public String toString() {
+        return "saddled {this} this turn";
+    }
+}

Mage/src/main/java/mage/watchers/common/SaddledMountWatcher.java

@@ -0,0 +1,55 @@
+package mage.watchers.common;
+
+import mage.MageObjectReference;
+import mage.constants.WatcherScope;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.game.permanent.Permanent;
+import mage.watchers.Watcher;
+
+import java.util.*;
+
+/**
+ * @author TheElk801
+ */
+public class SaddledMountWatcher extends Watcher {
+
+    private final Map<MageObjectReference, Set<MageObjectReference>> saddleMap = new HashMap<>();
+
+    public SaddledMountWatcher() {
+        super(WatcherScope.GAME);
+    }
+
+    @Override
+    public void watch(GameEvent event, Game game) {
+        if (event.getType() == GameEvent.EventType.SADDLED_MOUNT) {
+            saddleMap.computeIfAbsent(new MageObjectReference(event.getSourceId(), game), x -> new HashSet<>())
+                    .add(new MageObjectReference(event.getTargetId(), game));
+        }
+    }
+
+    @Override
+    public void reset() {
+        super.reset();
+        saddleMap.clear();
+    }
+
+    public static boolean checkIfSaddledThisTurn(Permanent saddler, Permanent mount, Game game) {
+        return game
+                .getState()
+                .getWatcher(SaddledMountWatcher.class)
+                .saddleMap
+                .getOrDefault(new MageObjectReference(mount, game), Collections.emptySet())
+                .stream()
+                .anyMatch(mor -> mor.refersTo(saddler, game));
+    }
+
+    public static int getSaddleCount(Permanent vehicle, Game game) {
+        return game
+                .getState()
+                .getWatcher(SaddledMountWatcher.class)
+                .saddleMap
+                .getOrDefault(new MageObjectReference(vehicle, game), Collections.emptySet())
+                .size();
+    }
+}