diff --git a/forge-ai/src/main/java/forge/ai/ComputerUtilCost.java b/forge-ai/src/main/java/forge/ai/ComputerUtilCost.java
index c5badd51b39..4fc55a2339d 100644
--- a/forge-ai/src/main/java/forge/ai/ComputerUtilCost.java
+++ b/forge-ai/src/main/java/forge/ai/ComputerUtilCost.java
@@ -657,6 +657,17 @@ public static int getMaxXValue(SpellAbility sa, Player ai, final boolean effect)
 
         if (root.costHasManaX()) {
             val = ComputerUtilMana.determineLeftoverMana(root, ai, effect);
+
+            if (sa.hasParam("AIMaxTgtCost")) {
+                String value = sa.getParam("AIMaxTgtCost");
+                String svar = source.getSVar(value);
+                if (svar.contains("LeftoverMana")) {
+                    // limit the CMC to available mana
+                    svar = svar.replace("LeftoverMana", ""+val);
+                }
+                int calculated = AbilityUtils.calculateAmount(source, svar, sa);
+                val = ObjectUtils.min(val, calculated);
+            }
         }
 
         if (sa.usesTargeting()) {
diff --git a/forge-gui-desktop/src/test/java/forge/ai/simulation/SpellAbilityPickerSimulationTest.java b/forge-gui-desktop/src/test/java/forge/ai/simulation/SpellAbilityPickerSimulationTest.java
index df3a5b2d282..6e1470c95c5 100644
--- a/forge-gui-desktop/src/test/java/forge/ai/simulation/SpellAbilityPickerSimulationTest.java
+++ b/forge-gui-desktop/src/test/java/forge/ai/simulation/SpellAbilityPickerSimulationTest.java
@@ -8,6 +8,7 @@
 import forge.item.PaperCard;
 import forge.model.FModel;
 import org.testng.AssertJUnit;
+import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
 import forge.game.Game;
@@ -897,4 +898,47 @@ public void testPithingNeedlePreventsAbilitiesFromBeingChosen() {
         game.getAction().checkStateEffects(true);
         AssertJUnit.assertNull(picker.chooseSpellAbilityToPlay(null));
     }
+
+    @DataProvider(name = "testXIsTheLargestPayableCMCData")
+    public static Object[][] testXIsTheLargestPayableCMCData() {
+        return new Object[][] {
+                {"Green Sun's Zenith"},
+                //{"Finale of Devastation"}, //X is not limited to allow reach 10 and gain +X/+X
+                //{"Rocco, Cabaretti Caterer"}, //not working: it is creature with TrigChangeZone
+                {"Chord of Calling"},
+                {"Nature's Rhythm"}
+        };
+    }
+
+    @Test(dataProvider = "testXIsTheLargestPayableCMCData")
+    public void testXIsTheLargestPayableCMC(String cardName) {
+        Game game = initAndCreateGame();
+        Player ai = game.getPlayers().get(1);
+        ai.setTeam(0);
+
+        Player opponent = game.getPlayers().get(0);
+        opponent.setTeam(1);
+
+        // 9 mana available
+        addCards("Forest", 3, ai);
+        addCards("Mountain", 3, ai);
+        addCards("Plains", 3, ai);
+
+        // the most expensive payable creature is Endurance with CMC=3
+        addCardToZone(cardName, ai, ZoneType.Hand);
+        addCardToZone("Birds of Paradise", ai, ZoneType.Library); //CMC 1 - subpar
+        addCardToZone("Grizzly Bears", ai, ZoneType.Library); //CMC 2 - subpar
+        addCardToZone("Endurance", ai, ZoneType.Library); //CMC 3 - maximum
+        addCardToZone("Apex Devastator", ai, ZoneType.Library); //CMC 10 - to much
+        addCardToZone("Emrakul, the Aeons Torn", ai, ZoneType.Library); //CMC 15 - to much
+
+        game.getPhaseHandler().devModeSet(PhaseType.MAIN2, ai);
+        game.getAction().checkStateEffects(true);
+        SpellAbilityPicker picker = new SpellAbilityPicker(game, ai);
+        SpellAbility sa = picker.chooseSpellAbilityToPlay(null);
+
+        AssertJUnit.assertNotNull(sa);
+        AssertJUnit.assertEquals("Card '%s' was cast with X instead".formatted(cardName), 3, sa.getXManaCostPaid().intValue());
+    }
+
 }
diff --git a/forge-gui/res/cardsfolder/c/chord_of_calling.txt b/forge-gui/res/cardsfolder/c/chord_of_calling.txt
index dabe0696e14..bca5a9ef867 100644
--- a/forge-gui/res/cardsfolder/c/chord_of_calling.txt
+++ b/forge-gui/res/cardsfolder/c/chord_of_calling.txt
@@ -2,6 +2,7 @@ Name:Chord of Calling
 ManaCost:X G G G
 Types:Instant
 K:Convoke
-A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.cmcLEX | ChangeNum$ 1 | StackDescription$ SpellDescription | SpellDescription$ Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
+A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.cmcLEX | ChangeNum$ 1 | StackDescription$ SpellDescription | AIMaxTgtCost$ Y | SpellDescription$ Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
 SVar:X:Count$xPaid
+SVar:Y:Count$ValidLibrary Creature.YouOwn+cmcLELeftoverMana$GreatestCardManaCost
 Oracle:Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)\nSearch your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
diff --git a/forge-gui/res/cardsfolder/f/finale_of_devastation.txt b/forge-gui/res/cardsfolder/f/finale_of_devastation.txt
index 63ba9d25c15..0e1c374250a 100644
--- a/forge-gui/res/cardsfolder/f/finale_of_devastation.txt
+++ b/forge-gui/res/cardsfolder/f/finale_of_devastation.txt
@@ -1,7 +1,7 @@
 Name:Finale of Devastation
 ManaCost:X G G
 Types:Sorcery
-A:SP$ ChangeZone | ChangeType$ Creature.YouCtrl+cmcLEX | Hidden$ True | Origin$ Library | OriginAlternative$ Graveyard | Destination$ Battlefield | ShuffleNonMandatory$ True | SubAbility$ DBPump | SpellDescription$ Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.
+A:SP$ ChangeZone | ChangeType$ Creature.YouCtrl+cmcLEX | ChangeTypeDesc$ creature | Hidden$ True | Origin$ Library | OriginAlternative$ Graveyard | Destination$ Battlefield | ShuffleNonMandatory$ True | SubAbility$ DBPump | SpellDescription$ Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.
 SVar:DBPump:DB$ PumpAll | ValidCards$ Creature.YouCtrl | KW$ Haste | NumAtt$ +X | NumDef$ +X | ConditionCheckSVar$ X | ConditionSVarCompare$ GE10 | StackDescription$ SpellDescription | SpellDescription$ If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.
 SVar:X:Count$xPaid
 Oracle:Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.
diff --git a/forge-gui/res/cardsfolder/g/green_suns_zenith.txt b/forge-gui/res/cardsfolder/g/green_suns_zenith.txt
index 1758679d888..146cc73cd35 100644
--- a/forge-gui/res/cardsfolder/g/green_suns_zenith.txt
+++ b/forge-gui/res/cardsfolder/g/green_suns_zenith.txt
@@ -1,7 +1,8 @@
 Name:Green Sun's Zenith
 ManaCost:X G
 Types:Sorcery
-A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.Green+cmcLEX | ChangeNum$ 1 | SubAbility$ DBShuffle | StackDescription$ Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. | SpellDescription$ Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle CARDNAME into its owner's library.
+A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.Green+cmcLEX | ChangeNum$ 1 | SubAbility$ DBShuffle | AIMaxTgtCost$ Y | StackDescription$ Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. | SpellDescription$ Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle CARDNAME into its owner's library.
 SVar:X:Count$xPaid
+SVar:Y:Count$ValidLibrary Creature.YouOwn+Green+cmcLELeftoverMana$GreatestCardManaCost
 SVar:DBShuffle:DB$ ChangeZone | Origin$ Stack | Destination$ Library | Shuffle$ True | Defined$ Parent
 Oracle:Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.
diff --git a/forge-gui/res/cardsfolder/n/natures_rhythm.txt b/forge-gui/res/cardsfolder/n/natures_rhythm.txt
index 19fd55e32e4..ed5fffdda3f 100644
--- a/forge-gui/res/cardsfolder/n/natures_rhythm.txt
+++ b/forge-gui/res/cardsfolder/n/natures_rhythm.txt
@@ -1,7 +1,8 @@
 Name:Nature's Rhythm
 ManaCost:X G G
 Types:Sorcery
-A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.cmcLEX | ChangeNum$ 1 | StackDescription$ SpellDescription | SpellDescription$ Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
+A:SP$ ChangeZone | Origin$ Library | Destination$ Battlefield | ChangeType$ Creature.cmcLEX | ChangeNum$ 1 | AIMaxTgtCost$ Y | StackDescription$ SpellDescription | SpellDescription$ Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.
 SVar:X:Count$xPaid
+SVar:Y:Count$ValidLibrary Creature.YouOwn+Green+cmcLELeftoverMana$GreatestCardManaCost
 K:Harmonize:X G G G G
 Oracle:Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.\nHarmonize {X}{G}{G}{G}{G} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by an amount of generic mana equal to its power. Then exile this spell.)