[MKM] Implement Tunnel Tipster (#11755)

* [MKM] Implement Tunnel Tipster

* Address PR comments

---------

Co-authored-by: Matthew Wilson <matthew_w@vaadin.com>

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

@@ -0,0 +1,108 @@
+package mage.cards.t;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+import mage.MageInt;
+import mage.abilities.Ability;
+import mage.abilities.common.BeginningOfEndStepTriggeredAbility;
+import mage.abilities.condition.Condition;
+import mage.abilities.effects.common.counter.AddCountersSourceEffect;
+import mage.abilities.hint.ConditionHint;
+import mage.abilities.mana.GreenManaAbility;
+import mage.constants.SubType;
+import mage.cards.CardImpl;
+import mage.cards.CardSetInfo;
+import mage.constants.CardType;
+import mage.constants.TargetController;
+import mage.constants.WatcherScope;
+import mage.constants.Zone;
+import mage.counters.CounterType;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.game.events.ZoneChangeEvent;
+import mage.watchers.Watcher;
+
+/**
+ *
+ * @author DominionSpy
+ */
+public final class TunnelTipster extends CardImpl {
+
+    public TunnelTipster(UUID ownerId, CardSetInfo setInfo) {
+        super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{1}{G}");
+
+        this.subtype.add(SubType.MOLE);
+        this.subtype.add(SubType.SCOUT);
+        this.power = new MageInt(1);
+        this.toughness = new MageInt(1);
+
+        // At the beginning of your end step, if a face-down creature entered the battlefield under your control this turn, put a +1/+1 counter on Tunnel Tipster.
+        Ability ability = new BeginningOfEndStepTriggeredAbility(
+                new AddCountersSourceEffect(CounterType.P1P1.createInstance()), TargetController.YOU,
+                TunnelTipsterCondition.instance, false);
+        ability.addHint(new ConditionHint(TunnelTipsterCondition.instance,
+                "a face-down creature entered the battlefield under your control"));
+        this.addAbility(ability, new TunnelTipsterWatcher());
+        // {T}: Add {G}.
+        this.addAbility(new GreenManaAbility());
+    }
+
+    private TunnelTipster(final TunnelTipster card) {
+        super(card);
+    }
+
+    @Override
+    public TunnelTipster copy() {
+        return new TunnelTipster(this);
+    }
+}
+
+class TunnelTipsterWatcher extends Watcher {
+
+    private final Set<UUID> players = new HashSet<>();
+
+    TunnelTipsterWatcher() {
+        super(WatcherScope.GAME);
+    }
+
+    @Override
+    public void watch(GameEvent event, Game game) {
+        if (event.getType() == GameEvent.EventType.ZONE_CHANGE) {
+            ZoneChangeEvent zEvent = (ZoneChangeEvent) event;
+            if (zEvent.getToZone() == Zone.BATTLEFIELD &&
+                    zEvent.getTarget().isCreature(game) &&
+                    zEvent.getTarget().isFaceDown(game)) {
+                players.add(zEvent.getTarget().getControllerId());
+            }
+        }
+    }
+
+    @Override
+    public void reset() {
+        super.reset();
+        players.clear();
+    }
+
+    public static boolean faceDownCreatureEnteredForPlayer(UUID playerId, Game game) {
+        return game
+                .getState()
+                .getWatcher(TunnelTipsterWatcher.class)
+                .players
+                .contains(playerId);
+    }
+}
+
+enum TunnelTipsterCondition implements Condition {
+    instance;
+
+    @Override
+    public boolean apply(Game game, Ability source) {
+        return TunnelTipsterWatcher.faceDownCreatureEnteredForPlayer(source.getControllerId(), game);
+    }
+
+    @Override
+    public String toString() {
+        return "a face-down creature entered the battlefield under your control this turn";
+    }
+}

Mage.Sets/src/mage/sets/MurdersAtKarlovManor.java

@@ -226,6 +226,7 @@ public final class MurdersAtKarlovManor extends ExpansionSet {
         cards.add(new SetCardInfo("Toxin Analysis", 107, Rarity.COMMON, mage.cards.t.ToxinAnalysis.class));
         cards.add(new SetCardInfo("Treacherous Greed", 237, Rarity.RARE, mage.cards.t.TreacherousGreed.class));
         cards.add(new SetCardInfo("Trostani, Three Whispers", 238, Rarity.MYTHIC, mage.cards.t.TrostaniThreeWhispers.class));
+        cards.add(new SetCardInfo("Tunnel Tipster", 180, Rarity.COMMON, mage.cards.t.TunnelTipster.class));
         cards.add(new SetCardInfo("Unauthorized Exit", 74, Rarity.COMMON, mage.cards.u.UnauthorizedExit.class));
         cards.add(new SetCardInfo("Undercity Eliminator", 108, Rarity.UNCOMMON, mage.cards.u.UndercityEliminator.class));
         cards.add(new SetCardInfo("Undercity Sewers", 270, Rarity.RARE, mage.cards.u.UndercitySewers.class));