diff --git a/Mage.Sets/src/mage/cards/s/SwimmerInNightmares.java b/Mage.Sets/src/mage/cards/s/SwimmerInNightmares.java
new file mode 100644
index 0000000000..a13f4e773c
--- /dev/null
+++ b/Mage.Sets/src/mage/cards/s/SwimmerInNightmares.java
@@ -0,0 +1,78 @@
+package mage.cards.s;
+
+import mage.MageInt;
+import mage.abilities.Ability;
+import mage.abilities.common.SimpleStaticAbility;
+import mage.abilities.condition.Condition;
+import mage.abilities.condition.common.PermanentsOnTheBattlefieldCondition;
+import mage.abilities.decorator.ConditionalContinuousEffect;
+import mage.abilities.decorator.ConditionalRestrictionEffect;
+import mage.abilities.effects.common.combat.CantBeBlockedSourceEffect;
+import mage.abilities.effects.common.continuous.BoostSourceEffect;
+import mage.cards.CardImpl;
+import mage.cards.CardSetInfo;
+import mage.constants.CardType;
+import mage.constants.Duration;
+import mage.constants.SubType;
+import mage.filter.FilterPermanent;
+import mage.filter.common.FilterControlledPlaneswalkerPermanent;
+import mage.game.Game;
+import mage.players.Player;
+
+import java.util.HashSet;
+import java.util.UUID;
+
+/**
+ * @author TheElk801
+ */
+public final class SwimmerInNightmares extends CardImpl {
+
+    private static final FilterPermanent filter = new FilterControlledPlaneswalkerPermanent(SubType.ASHIOK);
+    private static final Condition condition = new PermanentsOnTheBattlefieldCondition(filter);
+
+    public SwimmerInNightmares(UUID ownerId, CardSetInfo setInfo) {
+        super(ownerId, setInfo, new CardType[]{CardType.CREATURE}, "{2}{U}");
+
+        this.subtype.add(SubType.NIGHTMARE);
+        this.subtype.add(SubType.MERFOLK);
+        this.power = new MageInt(1);
+        this.toughness = new MageInt(4);
+
+        // Swimmer in Nightmares gets +3/+0 as long as there are ten or more cards in a single graveyard.
+        this.addAbility(new SimpleStaticAbility(new ConditionalContinuousEffect(
+                new BoostSourceEffect(3, 0, Duration.WhileOnBattlefield),
+                SwimmerInNightmaresCondition.instance,
+                "{this} +3/+0 as long as there are ten or more cards in a single graveyard"
+        )));
+
+        // Swimmer in Nightmares can't be blocked as long as you control an Ashiok planeswalker.
+        this.addAbility(new SimpleStaticAbility(new ConditionalRestrictionEffect(
+                new CantBeBlockedSourceEffect(), condition,
+                "{this} can't be blocked as long as you control an Ashiok planeswalker"
+        )));
+    }
+
+    private SwimmerInNightmares(final SwimmerInNightmares card) {
+        super(card);
+    }
+
+    @Override
+    public SwimmerInNightmares copy() {
+        return new SwimmerInNightmares(this);
+    }
+}
+
+enum SwimmerInNightmaresCondition implements Condition {
+    instance;
+
+    @Override
+    public boolean apply(Game game, Ability source) {
+        return game.getState()
+                .getPlayersInRange(source.getControllerId(), game)
+                .stream()
+                .map(game::getPlayer)
+                .map(Player::getGraveyard)
+                .map(HashSet::size)
+                .anyMatch(x -> x >= 10);
+    }
+}
\ No newline at end of file
diff --git a/Mage.Sets/src/mage/sets/TherosBeyondDeath.java b/Mage.Sets/src/mage/sets/TherosBeyondDeath.java
index 7ec690ee4c..2e33cae432 100644
--- a/Mage.Sets/src/mage/sets/TherosBeyondDeath.java
+++ b/Mage.Sets/src/mage/sets/TherosBeyondDeath.java
@@ -138,6 +138,7 @@ public final class TherosBeyondDeath extends ExpansionSet {
         cards.add(new SetCardInfo("Storm's Wrath", 157, Rarity.RARE, mage.cards.s.StormsWrath.class));
         cards.add(new SetCardInfo("Swamp", 252, Rarity.LAND, mage.cards.basiclands.Swamp.class, FULL_ART_BFZ_VARIOUS));
         cards.add(new SetCardInfo("Sweet Oblivion", 70, Rarity.UNCOMMON, mage.cards.s.SweetOblivion.class));
+        cards.add(new SetCardInfo("Swimmer in Nightmares", 275, Rarity.UNCOMMON, mage.cards.s.SwimmerInNightmares.class));
         cards.add(new SetCardInfo("Taranika, Akroan Veteran", 39, Rarity.RARE, mage.cards.t.TaranikaAkroanVeteran.class));
         cards.add(new SetCardInfo("Tectonic Giant", 158, Rarity.RARE, mage.cards.t.TectonicGiant.class));
         cards.add(new SetCardInfo("Temple of Abandon", 244, Rarity.RARE, mage.cards.t.TempleOfAbandon.class));