added support for special lands in M20

Mage.Sets/src/mage/sets/CoreSet2020.java

@@ -1,9 +1,16 @@
 package mage.sets;
 
 import mage.cards.ExpansionSet;
+import mage.cards.repository.CardCriteria;
+import mage.cards.repository.CardInfo;
+import mage.cards.repository.CardRepository;
+import mage.constants.CardType;
 import mage.constants.Rarity;
 import mage.constants.SetType;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * @author TheElk801
  */
@@ -15,6 +22,9 @@ public static CoreSet2020 getInstance() {
         return instance;
     }
 
+    List<CardInfo> savedSpecialCommon = new ArrayList<>();
+    protected final List<CardInfo> savedSpecialLand = new ArrayList<>();
+
     private CoreSet2020() {
         super("Core Set 2020", "M20", ExpansionSet.buildDate(2019, 7, 12), SetType.CORE);
         this.hasBoosters = true;
@@ -27,6 +37,11 @@ private CoreSet2020() {
         this.ratioBoosterMythic = 8;
         this.maxCardNumberInBooster = 280;
 
+        // Core 2020 boosters have a 5/12 chance of basic land being replaced
+        // with the common taplands, which DO NOT appear in the common slot.
+        this.ratioBoosterSpecialLand = 12;
+        this.ratioBoosterSpecialLandNumerator = 5;
+
         cards.add(new SetCardInfo("Aerial Assault", 1, Rarity.COMMON, mage.cards.a.AerialAssault.class));
         cards.add(new SetCardInfo("Agent of Treachery", 43, Rarity.RARE, mage.cards.a.AgentOfTreachery.class));
         cards.add(new SetCardInfo("Ajani, Strength of the Pride", 2, Rarity.MYTHIC, mage.cards.a.AjaniStrengthOfThePride.class));
@@ -155,4 +170,40 @@ private CoreSet2020() {
         cards.add(new SetCardInfo("Yarok's Fenlurker", 123, Rarity.UNCOMMON, mage.cards.y.YaroksFenlurker.class));
         cards.add(new SetCardInfo("Yarok, the Desecrated", 220, Rarity.MYTHIC, mage.cards.y.YarokTheDesecrated.class));
     }
+
+    @Override
+    public List<CardInfo> getCardsByRarity(Rarity rarity) {
+        // Common cards retrievement of Core Set 2020 boosters - prevent the retrievement of the common lands
+        if (rarity == Rarity.COMMON) {
+            List<CardInfo> savedCardsInfos = savedCards.get(rarity);
+            if (savedCardsInfos == null) {
+                CardCriteria criteria = new CardCriteria();
+                criteria.rarities(Rarity.COMMON);
+                criteria.setCodes(this.code).notTypes(CardType.LAND);
+                savedCardsInfos = CardRepository.instance.findCards(criteria);
+                if (maxCardNumberInBooster != Integer.MAX_VALUE) {
+                    savedCardsInfos.removeIf(next -> next.getCardNumberAsInt() > maxCardNumberInBooster && rarity != Rarity.LAND);
+                }
+                savedCards.put(rarity, savedCardsInfos);
+            }
+            // Return a copy of the saved cards information, as not to let modify the original.
+            return new ArrayList<>(savedCardsInfos);
+        } else {
+            return super.getCardsByRarity(rarity);
+        }
+    }
+
+    @Override
+    // the common taplands replacing the basic land
+    public List<CardInfo> getSpecialLand() {
+        if (savedSpecialLand.isEmpty()) {
+            CardCriteria criteria = new CardCriteria();
+            criteria.setCodes(this.code);
+            criteria.rarities(Rarity.COMMON);
+            criteria.types(CardType.LAND);
+            savedSpecialLand.addAll(CardRepository.instance.findCards(criteria));
+        }
+
+        return new ArrayList<>(savedSpecialLand);
+    }
 }