[LTR] Implement The Balrog, Durin's Bane (#10515)

* [LTR] Implement The Balrog, Durin's Bane

I could use someone more experienced for this card:
Should the watcher `PermanentsSacrificedWatcher` be initialized locally in the card's class, or is a global initializing in GameImpl.java alright? I went for the latter for now, as my base for implementing the static cost reduction was Blood for the Blood God!

* apply review

* no longer instantiate watcher on every game.

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

@@ -0,0 +1,79 @@
+package mage.cards.t;
+
+import mage.MageInt;
+import mage.abilities.Ability;
+import mage.abilities.common.DiesSourceTriggeredAbility;
+import mage.abilities.common.SimpleEvasionAbility;
+import mage.abilities.common.SimpleStaticAbility;
+import mage.abilities.dynamicvalue.common.PermanentsSacrificedThisTurnCount;
+import mage.abilities.effects.common.DestroyTargetEffect;
+import mage.abilities.effects.common.combat.CantBeBlockedByCreaturesSourceEffect;
+import mage.abilities.effects.common.cost.SpellCostReductionSourceEffect;
+import mage.abilities.hint.common.PermanentsSacrificedThisTurnHint;
+import mage.abilities.keyword.HasteAbility;
+import mage.cards.CardImpl;
+import mage.cards.CardSetInfo;
+import mage.constants.*;
+import mage.filter.StaticFilters;
+import mage.filter.common.FilterCreaturePermanent;
+import mage.filter.predicate.Predicates;
+import mage.target.TargetPermanent;
+import mage.watchers.common.PermanentsSacrificedWatcher;
+
+import java.util.UUID;
+
+/**
+ *
+ * @author Susucr
+ */
+public final class TheBalrogDurinsBane extends CardImpl {
+
+    private static final FilterCreaturePermanent filterNonLegendary
+        = new FilterCreaturePermanent("except by legendary creatures");
+
+    static {
+        filterNonLegendary.add(Predicates.not(SuperType.LEGENDARY.getPredicate()));
+    }
+
+    public TheBalrogDurinsBane(UUID ownerId, CardSetInfo setInfo) {
+        super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{5}{B}{R}");
+        
+        this.supertype.add(SuperType.LEGENDARY);
+        this.subtype.add(SubType.AVATAR);
+        this.subtype.add(SubType.DEMON);
+        this.power = new MageInt(7);
+        this.toughness = new MageInt(5);
+
+        // This spell costs {1} less to cast for each permanent sacrificed this turn.
+        this.addAbility(
+            new SimpleStaticAbility(
+                Zone.ALL,
+                new SpellCostReductionSourceEffect(PermanentsSacrificedThisTurnCount.instance)
+                    .setText("this spell costs {1} less to cast for each permanent sacrificed this turn")
+            ).addHint(PermanentsSacrificedThisTurnHint.instance).setRuleAtTheTop(true),
+            new PermanentsSacrificedWatcher()
+        );
+
+        // Haste
+        this.addAbility(HasteAbility.getInstance());
+
+        // The Balrog, Durin's Bane can't be blocked except by legendary creatures.
+        this.addAbility(new SimpleEvasionAbility((new CantBeBlockedByCreaturesSourceEffect(
+            filterNonLegendary, Duration.WhileOnBattlefield
+        ))));
+
+        // When The Balrog dies, destroy target artifact or creature an opponent controls.
+        Ability ability = new DiesSourceTriggeredAbility(new DestroyTargetEffect());
+        ability.addTarget(new TargetPermanent(StaticFilters.FILTER_OPPONENTS_PERMANENT_ARTIFACT_OR_CREATURE));
+        this.addAbility(ability);
+    }
+
+    private TheBalrogDurinsBane(final TheBalrogDurinsBane card) {
+        super(card);
+    }
+
+    @Override
+    public TheBalrogDurinsBane copy() {
+        return new TheBalrogDurinsBane(this);
+    }
+}

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

@@ -251,6 +251,7 @@ public final class TheLordOfTheRingsTalesOfMiddleEarth extends ExpansionSet {
         cards.add(new SetCardInfo("Swamp", 266, Rarity.LAND, mage.cards.basiclands.Swamp.class, NON_FULL_USE_VARIOUS));
         cards.add(new SetCardInfo("Swarming of Moria", 150, Rarity.COMMON, mage.cards.s.SwarmingOfMoria.class));
         cards.add(new SetCardInfo("Tale of Tinuviel", 34, Rarity.UNCOMMON, mage.cards.t.TaleOfTinuviel.class));
+        cards.add(new SetCardInfo("The Balrog, Durin's Bane", 195, Rarity.RARE, mage.cards.t.TheBalrogDurinsBane.class));
         cards.add(new SetCardInfo("The Balrog, Flame of Udun", 297, Rarity.RARE, mage.cards.t.TheBalrogFlameOfUdun.class));
         cards.add(new SetCardInfo("The Bath Song", 40, Rarity.UNCOMMON, mage.cards.t.TheBathSong.class));
         cards.add(new SetCardInfo("The Battle of Bywater", 2, Rarity.RARE, mage.cards.t.TheBattleOfBywater.class));

Mage/src/main/java/mage/abilities/dynamicvalue/common/PermanentsSacrificedThisTurnCount.java

@@ -0,0 +1,40 @@
+
+package mage.abilities.dynamicvalue.common;
+
+import mage.abilities.Ability;
+import mage.abilities.dynamicvalue.DynamicValue;
+import mage.abilities.effects.Effect;
+import mage.game.Game;
+import mage.watchers.common.PermanentsSacrificedWatcher;
+
+/**
+ * @author Susucr
+ */
+public enum PermanentsSacrificedThisTurnCount implements DynamicValue {
+    instance;
+
+    @Override
+    public int calculate(Game game, Ability sourceAbility, Effect effect) {
+        PermanentsSacrificedWatcher watcher = game.getState().getWatcher(PermanentsSacrificedWatcher.class);
+        if (watcher != null) {
+            return watcher.getThisTurnSacrificedPermanents();
+        }
+        return 0;
+    }
+
+    @Override
+    public PermanentsSacrificedThisTurnCount copy() {
+        return PermanentsSacrificedThisTurnCount.instance;
+    }
+
+    @Override
+    public String toString() {
+        return "X";
+    }
+
+    @Override
+    public String getMessage() {
+        return "permanents sacrificed this turn";
+    }
+
+}

Mage/src/main/java/mage/abilities/hint/common/PermanentsSacrificedThisTurnHint.java

@@ -0,0 +1,28 @@
+package mage.abilities.hint.common;
+
+import mage.abilities.Ability;
+import mage.abilities.dynamicvalue.common.PermanentsSacrificedThisTurnCount;
+import mage.abilities.hint.Hint;
+import mage.abilities.hint.ValueHint;
+import mage.game.Game;
+
+/**
+ * @author Susucr
+ */
+public enum PermanentsSacrificedThisTurnHint implements Hint {
+    instance;
+
+    private static final Hint hint = new ValueHint(
+            "Permanents sacrificed this turn", PermanentsSacrificedThisTurnCount.instance
+    );
+
+    @Override
+    public String getText(Game game, Ability ability) {
+        return hint.getText(game, ability);
+    }
+
+    @Override
+    public PermanentsSacrificedThisTurnHint copy() {
+        return this;
+    }
+}

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

@@ -46,4 +46,8 @@ public class PermanentsSacrificedWatcher extends Watcher {
     public List<Permanent> getThisTurnSacrificedPermanents(UUID playerId) {
         return sacrificedPermanents.get(playerId);
     }
+
+    public int getThisTurnSacrificedPermanents() {
+        return sacrificedPermanents.values().stream().mapToInt(permanents -> permanents.size()).sum();
+    }
 }