May spend Mana only work on Stack

forge-gui/res/cardsfolder/e/emissarys_ploy.txt

@@ -2,6 +2,6 @@ Name:Emissary's Ploy
 Types:Conspiracy
 Text:(Start the game with this conspiracy face up in the command zone.)
 K:Before drawing your opening hand, choose 1, 2, or 3.
-S:Mode$ Continuous| Affected$ Creature.YouCtrl+cmcEQX | AffectedZone$ Hand,Library,Graveyard,Exile,Command | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | Description$ You may spend mana as though it were mana of any color to cast creature spells with converted mana cost equal to the chosen number.
+S:Mode$ Continuous | Affected$ Creature.YouCtrl+cmcEQX | AffectedZone$ Stack | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | Description$ You may spend mana as though it were mana of any color to cast creature spells with converted mana cost equal to the chosen number.
 SVar:X:Count$ChosenNumber
 Oracle:(Start the game with this conspiracy face up in the command zone.)\nBefore drawing your opening hand, choose 1, 2, or 3. You may spend mana as though it were mana of any color to cast creature spells with converted mana cost equal to the chosen number.

forge-gui/res/cardsfolder/o/oath_of_nissa.txt

@@ -3,6 +3,5 @@ ManaCost:G
 Types:Legendary Enchantment
 T:Mode$ ChangesZone | ValidCard$ Card.Self | Origin$ Any | Destination$ Battlefield | Execute$ TrigDig | TriggerDescription$ When CARDNAME enters the battlefield, look at the top three cards of your library. You may reveal a creature, land, or planeswalker card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
 SVar:TrigDig:DB$Dig | DigNum$ 3 | ChangeNum$ 1 | Optional$ True | ChangeValid$ Creature,Land,Planeswalker
-S:Mode$ Continuous| Affected$ Planeswalker.YouCtrl | AffectedZone$ Hand,Library,Graveyard,Exile,Command | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | Description$ You may spend mana as though it were mana of any color to cast planeswalker spells.
+S:Mode$ Continuous | Affected$ Planeswalker.YouCtrl | AffectedZone$ Stack | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | Description$ You may spend mana as though it were mana of any color to cast planeswalker spells.
-SVar:Picture:http://www.wizards.com/global/images/magic/general/oath_of_nissa.jpg
 Oracle:When Oath of Nissa enters the battlefield, look at the top three cards of your library. You may reveal a creature, land, or planeswalker card from among them and put it into your hand. Put the rest on the bottom of your library in any order.\nYou may spend mana as though it were mana of any color to cast planeswalker spells.

forge-gui/res/cardsfolder/u/unexpected_potential.txt

@@ -2,6 +2,6 @@ Name:Unexpected Potential
 ManaCost:no cost
 Types:Conspiracy
 K:Hidden agenda
-S:Mode$ Continuous | EffectZone$ Command | Affected$ Card.NamedCard | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | AffectedZone$ Hand,Graveyard,Exile,Library,Command | Description$ You may spend mana as though it were mana of any color to cast spells with the chosen name.
+S:Mode$ Continuous | EffectZone$ Command | Affected$ Card.NamedCard | AffectedZone$ Stack | AddHiddenKeyword$ May spend mana as though it were mana of any color to cast CARDNAME | Description$ You may spend mana as though it were mana of any color to cast spells with the chosen name.
 SVar:AgendaLogic:BestCreatureInComputerDeck
 Oracle:Hidden agenda (Start the game with this conspiracy face down in the command zone and secretly name a card. You may turn this conspiracy face up any time and reveal the chosen name.)\nYou may spend mana as though it were mana of any color to cast spells with the chosen name.

forge-gui/res/cardsfolder/v/vizier_of_the_menagerie.txt

@@ -4,5 +4,5 @@ Types:Creature Naga Cleric
 PT:3/4
 S:Mode$ Continuous | Affected$ Card.TopLibrary+YouCtrl | AffectedZone$ Library | MayLookAt$ You | Description$ You may look at the top card of your library any time.
 S:Mode$ Continuous | Affected$ Creature.TopLibrary+YouCtrl+nonLand | AffectedZone$ Library | MayPlay$ True | Description$ You may cast the top card of your library if it's a creature card.
-S:Mode$ Continuous | AddHiddenKeyword$ May spend mana as though it were mana of any type to cast CARDNAME | Affected$ Card.Creature+nonLand | AffectedZone$ Library,Hand,Graveyard,Exile | Description$ You may spend mana as though it were mana of any type to cast creature spells.
+S:Mode$ Continuous | Affected$ Creature.YouCtrl | AffectedZone$ Stack | AddHiddenKeyword$ May spend mana as though it were mana of any type to cast CARDNAME | Description$ You may spend mana as though it were mana of any type to cast creature spells.
 Oracle:You may look at the top card of your library any time.\nYou may cast the top card of your library if it's a creature card.\nYou may spend mana as though it were mana of any type to cast creature spells.

forge-gui/src/main/java/forge/player/HumanPlaySpellAbility.java

@@ -74,24 +74,11 @@ public class HumanPlaySpellAbility {
         boolean manaTypeConversion = false;
         boolean manaColorConversion = false;
 
-        if (ability.isSpell()) {
-            if (c.hasKeyword("May spend mana as though it were mana of any type to cast CARDNAME")
-                    || (option != null && option.isIgnoreManaCostType())) {
-                manaTypeConversion = true;
-            } else  if (c.hasKeyword("May spend mana as though it were mana of any color to cast CARDNAME")
-                    || (option != null && option.isIgnoreManaCostColor())) {
-                manaColorConversion = true;
-            }
-        }
-        
-        final boolean playerManaConversion = human.hasManaConversion()
-                && human.getController().confirmAction(ability, null, "Do you want to spend mana as though it were mana of any color to pay the cost?");
-
         boolean keywordColor = false;
         // freeze Stack. No abilities should go onto the stack while I'm filling requirements.
         game.getStack().freezeStack();
 
-        if (ability instanceof Spell && !c.isCopiedSpell()) {
+        if (ability.isSpell() && !c.isCopiedSpell()) {
             fromZone = game.getZoneOf(c);
             fromState = c.getCurrentStateName();
             if (fromZone != null) {
@@ -111,6 +98,20 @@ public class HumanPlaySpellAbility {
 
         ability = GameActionUtil.addExtraKeywordCost(ability);
 
+        if (ability.isSpell() && !ability.isCopied()) { // These hidden keywords should only apply on the Stack
+            final Card host = ability.getHostCard();
+            if (host.hasKeyword("May spend mana as though it were mana of any type to cast CARDNAME")
+                    || (option != null && option.isIgnoreManaCostType())) {
+                manaTypeConversion = true;
+            } else if (host.hasKeyword("May spend mana as though it were mana of any color to cast CARDNAME")
+                    || (option != null && option.isIgnoreManaCostColor())) {
+                manaColorConversion = true;
+            }
+        }
+
+        final boolean playerManaConversion = human.hasManaConversion()
+                && human.getController().confirmAction(ability, null, "Do you want to spend mana as though it were mana of any color to pay the cost?");
+
         Cost abCost = ability.getPayCosts();
         CostPayment payment = new CostPayment(abCost, ability);