diff --git a/Mage.Sets/src/mage/cards/t/TheoreticalDuplication.java b/Mage.Sets/src/mage/cards/t/TheoreticalDuplication.java
new file mode 100644
index 0000000000..03b6b2b61f
--- /dev/null
+++ b/Mage.Sets/src/mage/cards/t/TheoreticalDuplication.java
@@ -0,0 +1,83 @@
+package mage.cards.t;
+
+import mage.abilities.DelayedTriggeredAbility;
+import mage.abilities.effects.common.CreateDelayedTriggeredAbilityEffect;
+import mage.abilities.effects.common.CreateTokenCopyTargetEffect;
+import mage.cards.CardImpl;
+import mage.cards.CardSetInfo;
+import mage.constants.CardType;
+import mage.constants.Duration;
+import mage.game.Game;
+import mage.game.events.EntersTheBattlefieldEvent;
+import mage.game.events.GameEvent;
+import mage.game.permanent.PermanentToken;
+import mage.target.targetpointer.FixedTarget;
+
+import java.util.UUID;
+
+/**
+ * @author TheElk801
+ */
+public final class TheoreticalDuplication extends CardImpl {
+
+    public TheoreticalDuplication(UUID ownerId, CardSetInfo setInfo) {
+        super(ownerId, setInfo, new CardType[]{CardType.INSTANT}, "{2}{U}");
+
+        // Whenever a nontoken creature enters the battlefield under an opponent's control this turn, create a token that's a copy of that creature.
+        this.getSpellAbility().addEffect(new CreateDelayedTriggeredAbilityEffect(new TheoreticalDuplicationTriggeredAbility()));
+    }
+
+    private TheoreticalDuplication(final TheoreticalDuplication card) {
+        super(card);
+    }
+
+    @Override
+    public TheoreticalDuplication copy() {
+        return new TheoreticalDuplication(this);
+    }
+}
+
+class TheoreticalDuplicationTriggeredAbility extends DelayedTriggeredAbility {
+
+    private static final CreateTokenCopyTargetEffect makeEffect() {
+        CreateTokenCopyTargetEffect effect = new CreateTokenCopyTargetEffect();
+        effect.setUseLKI(true);
+        return effect;
+    }
+
+    TheoreticalDuplicationTriggeredAbility() {
+        super(makeEffect(), Duration.EndOfTurn, false, false);
+    }
+
+    private TheoreticalDuplicationTriggeredAbility(final TheoreticalDuplicationTriggeredAbility ability) {
+        super(ability);
+    }
+
+    @Override
+    public boolean checkEventType(GameEvent event, Game game) {
+        return event.getType() == GameEvent.EventType.ENTERS_THE_BATTLEFIELD;
+    }
+
+    @Override
+    public boolean checkTrigger(GameEvent event, Game game) {
+        EntersTheBattlefieldEvent eEvent = (EntersTheBattlefieldEvent) event;
+        if (!eEvent.getTarget().isCreature()
+                || eEvent.getTarget() instanceof PermanentToken
+                || !game.getOpponents(getControllerId()).contains(eEvent.getTarget().getControllerId())) {
+            return false;
+        }
+        getEffects().setTargetPointer(new FixedTarget(eEvent.getTarget(), game));
+        return true;
+    }
+
+    @Override
+    public TheoreticalDuplicationTriggeredAbility copy() {
+        return new TheoreticalDuplicationTriggeredAbility(this);
+    }
+
+    @Override
+    public String getRule() {
+        return "Whenever a nontoken creature enters the battlefield under an opponent's control this turn, " +
+                "create a token that's a copy of that creature.";
+    }
+}
diff --git a/Mage.Sets/src/mage/sets/Commander2021Edition.java b/Mage.Sets/src/mage/sets/Commander2021Edition.java
index c243a6e987..bb028e5c15 100644
--- a/Mage.Sets/src/mage/sets/Commander2021Edition.java
+++ b/Mage.Sets/src/mage/sets/Commander2021Edition.java
@@ -300,6 +300,7 @@ public final class Commander2021Edition extends ExpansionSet {
         cards.add(new SetCardInfo("Tempting Contract", 78, Rarity.RARE, mage.cards.t.TemptingContract.class));
         cards.add(new SetCardInfo("Terastodon", 207, Rarity.RARE, mage.cards.t.Terastodon.class));
         cards.add(new SetCardInfo("Teysa, Envoy of Ghosts", 230, Rarity.RARE, mage.cards.t.TeysaEnvoyOfGhosts.class));
+        cards.add(new SetCardInfo("Theoretical Duplication", 34, Rarity.RARE, mage.cards.t.TheoreticalDuplication.class));
         cards.add(new SetCardInfo("Thopter Engineer", 181, Rarity.UNCOMMON, mage.cards.t.ThopterEngineer.class));
         cards.add(new SetCardInfo("Thousand-Year Elixir", 271, Rarity.RARE, mage.cards.t.ThousandYearElixir.class));
         cards.add(new SetCardInfo("Tivash, Gloom Summoner", 45, Rarity.RARE, mage.cards.t.TivashGloomSummoner.class));