*Reverted the Leylines to their previous handling as I thought ChangeZone could handle their "opening hand abilities".

res/cardsfolder/l/leyline_of_anticipation.txt

@@ -3,8 +3,6 @@ ManaCost:2 U U
 Types:Enchantment
 Text:If CARDNAME is in your opening hand, you may begin the game with it on the battlefield.
 S:Mode$ Continuous | Affected$ Card.nonLand+YouCtrl | AddKeyword$ HIDDEN Flash | AffectedZone$ Hand,Graveyard,Exile | Description$ You may cast nonland cards as though they had flash. (You may cast them any time you could cast an instant.)
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_anticipation.jpg

res/cardsfolder/l/leyline_of_lifeforce.txt

@@ -3,8 +3,6 @@ ManaCost:2 G G
 Types:Enchantment
 Text:If CARDNAME is in your opening hand, you may begin the game with it on the battlefield.
 S:Mode$ Continuous | Affected$ Creature | AddKeyword$ HIDDEN CARDNAME can't be countered. | AffectedZone$ Stack | Description$ Creature spells can't be countered.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_lifeforce.jpg

res/cardsfolder/l/leyline_of_lightning.txt

@@ -4,8 +4,6 @@ Types:Enchantment
 Text:If Leyline of Lightning is in your opening hand, you may begin the game with it on the battlefield.
 T:Mode$ SpellCast | ValidCard$ Card.YouCtrl | TriggerZones$ Battlefield | Execute$ TrigDealDamage | TriggerDescription$ Whenever you cast a spell, you may pay 1. If you do, CARDNAME deals 1 damage to target player.
 SVar:TrigDealDamage:AB$DealDamage | Cost$ 1 | Tgt$ TgtP | NumDmg$ 1
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_lightning.jpg

res/cardsfolder/l/leyline_of_punishment.txt

@@ -2,8 +2,6 @@ Name:Leyline of Punishment
 ManaCost:2 R R
 Types:Enchantment
 Text:If Leyline of Punishment is in your opening hand, you may begin the game with it on the battlefield. Players can't gain life. Damage can't be prevented.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_punishment.jpg

res/cardsfolder/l/leyline_of_sanctity.txt

@@ -2,8 +2,6 @@ Name:Leyline of Sanctity
 ManaCost:2 W W
 Types:Enchantment
 Text:If CARDNAME is in your opening hand, you may begin the game with it on the battlefield.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 S:Mode$ Continuous | Affected$ You | AddKeyword$ Hexproof | Description$ You have hexproof. (You can't be the target of spells or abilities your opponents control.)
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_sanctity.jpg

res/cardsfolder/l/leyline_of_singularity.txt

@@ -2,8 +2,6 @@ Name:Leyline of Singularity
 ManaCost:2 U U
 Types:Enchantment
 Text:If Leyline of Singularity is in your opening hand, you may begin the game with it on the battlefield.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 S:Mode$ Continuous | Affected$ Permanent.nonLand | AddType$ Legendary | Description$ All nonland permanents are legendary.
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare

res/cardsfolder/l/leyline_of_the_meek.txt

@@ -2,8 +2,6 @@ Name:Leyline of the Meek
 ManaCost:2 W W
 Types:Enchantment
 Text:If Leyline of the Meek is in your opening hand, you may begin the game with it on the battlefield.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 S:Mode$ Continuous | Affected$ Creature.token | AddPower$ 1 | AddToughness$ 1 | Description$ Creature tokens get +1/+1.
 SVar:PlayMain1:TRUE
 SVar:RemRandomDeck:True

res/cardsfolder/l/leyline_of_the_void.txt

@@ -2,8 +2,6 @@ Name:Leyline of the Void
 ManaCost:2 B B
 Types:Enchantment
 Text:If Leyline of the Void is in your opening hand, you may begin the game with it on the battlefield.\r\nIf a card would be put into an opponent's graveyard from anywhere, exile it instead.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 SVar:RemRandomDeck:True
 SVar:Rarity:Rare
 SVar:Picture:http://www.wizards.com/global/images/magic/general/leyline_of_the_void.jpg

res/cardsfolder/l/leyline_of_vitality.txt

@@ -2,8 +2,6 @@ Name:Leyline of Vitality
 ManaCost:2 G G
 Types:Enchantment
 Text:If Leyline of Vitality is in your opening hand, you may begin the game with it on the battlefield.
-K:MayEffectFromOpeningHand:PutOnBattlefield
-SVar:PutOnBattlefield:AB$ ChangeZone | Cost$ 0 | Defined$ Self | Origin$ Hand | Destination$ Battlefield
 S:Mode$ Continuous | Affected$ Creature.YouCtrl | AddToughness$ 1 | Description$ Creatures you control get +0/+1.
 T:Mode$ ChangesZone | Origin$ Any | Destination$ Battlefield | ValidCard$ Creature.YouCtrl | TriggerZones$ Battlefield | OptionalDecider$ You | Execute$ TrigGainLife | TriggerDescription$ Whenever a creature enters the battlefield under your control, you may gain 1 life.
 SVar:TrigGainLife:AB$GainLife | Cost$ 0 | Defined$ You | LifeAmount$ 1

src/main/java/forge/gui/input/Input_Mulligan.java

@@ -111,13 +111,16 @@ public class Input_Mulligan extends Input {
                     }
                 }
             }
+            if (c.getName().startsWith("Leyline")) {
+                if (GameActionUtil.showYesNoDialog(c, "Use this card's ability?"))
+                    AllZone.getGameAction().moveToPlay(c);
+            }
         }
 
         //Computer Leylines & Chancellors
         CardList aiOpeningHand = AllZoneUtil.getPlayerHand(AllZone.getComputerPlayer());
         for (Card c : aiOpeningHand) {
-            if (!(c.getName().startsWith("Leyline of Singularity")
+            if (!c.getName().startsWith("Leyline")) {
-                    && AllZoneUtil.getCardsInPlay("Leyline of Singularity").size() > 0)) {
                 ArrayList<String> kws = c.getKeyword(); 
                 for(int i = 0;i<kws.size();i++) {
                     String kw = kws.get(i);
@@ -136,7 +139,11 @@ public class Input_Mulligan extends Input {
                     }
                 }
             }
-
+			if (c.getName().startsWith("Leyline") && !(c.getName().startsWith("Leyline of Singularity")
+                    && AllZoneUtil.getCardsInPlay("Leyline of Singularity").size() > 0)) {
+                AllZone.getGameAction().moveToPlay(c);
+                AllZone.getGameAction().checkStateEffects();
+            }
         }
         AllZone.getGameAction().checkStateEffects();