[STX] Implemented Stonebound Mentor

Mage/src/main/java/mage/abilities/common/CardsLeaveGraveyardTriggeredAbility.java

@@ -0,0 +1,54 @@
+package mage.abilities.common;
+
+import mage.abilities.TriggeredAbilityImpl;
+import mage.abilities.effects.Effect;
+import mage.cards.Card;
+import mage.constants.Zone;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.game.events.ZoneChangeGroupEvent;
+
+import java.util.Objects;
+
+/**
+ * @author TheElk801
+ */
+public class CardsLeaveGraveyardTriggeredAbility extends TriggeredAbilityImpl {
+
+    public CardsLeaveGraveyardTriggeredAbility(Effect effect) {
+        super(Zone.BATTLEFIELD, effect, false);
+    }
+
+    private CardsLeaveGraveyardTriggeredAbility(final CardsLeaveGraveyardTriggeredAbility ability) {
+        super(ability);
+    }
+
+    @Override
+    public boolean checkEventType(GameEvent event, Game game) {
+        return event.getType() == GameEvent.EventType.ZONE_CHANGE_GROUP;
+    }
+
+    @Override
+    public boolean checkTrigger(GameEvent event, Game game) {
+        ZoneChangeGroupEvent zEvent = (ZoneChangeGroupEvent) event;
+        return zEvent != null
+                && Zone.GRAVEYARD == zEvent.getFromZone()
+                && Zone.GRAVEYARD != zEvent.getToZone()
+                && zEvent.getCards() != null
+                && zEvent.getCards()
+                .stream()
+                .filter(Objects::nonNull)
+                .map(Card::getOwnerId)
+                .anyMatch(this::isControlledBy);
+    }
+
+    @Override
+    public CardsLeaveGraveyardTriggeredAbility copy() {
+        return new CardsLeaveGraveyardTriggeredAbility(this);
+    }
+
+    @Override
+    public String getRule() {
+        return "Whenever one or more cards leave your graveyard, " + super.getRule();
+    }
+}