Don't be afraid to Mulligan, especially with the new rules towards it. You may draw only a few Leylines at first but Mulligan into 4. That's the difference between starting with them all on the field and having to spend mana to cast them all. Which could be the very difference between winning or losing the game unfortunately.
Modern
I thought a Modern/Casual deck around Starfield of Nyx would be pretty fun. Running the Leylines Enchantments. Starting the game with the most enchantments already in play as possible and then quickly getting Starfield out to turn them all into creatures.


Leyline of Sanctity You cannot be targeted by the opponent's spells or abilities. A 4/4 creature.
Leyline of Anticipation gives everything Flash. 4/4 as a creature.
Leyline of Lightning
let's you pay and deal 1 damage whenever you cast a spell. Also a 4/4 creature.
Leyline of Punishment cannot gain life or prevent damage. Another 4/4 creature.
Leyline of the Void stop recurring decks in their tracks.
Leyline of Vitality isn't that good since you won't be casting creatures.
Leyline of Lifeforce
, Leyline of Singularity, and
Leyline of the Meek
are pointless unfortunately.
and
Abundant Growth
, while it doesn't become animated by the Starfield, is there to help hit the five threshold quickly. You can use any one-drop Enchantment in it's place. (Maybe
Karametra's Favor
? But I don't think it would work since Enchantments are not Creatures and valid Enchant targets for this until Starfield is out actually.)
Aqueous Form is a good one. Lets you sift through the top of your deck for what you want and it makes your Enchantment turned Creatures unblockable so they can finish the job that much quicker.
Ethereal Armor just has crazy synergy with Enchantments. ( Eidolon of Countless Battles /
Helm of the Gods
too. )
Often you'll start the game with two or three Leylines on the battlefield and will need a little extra to hit five.
I'm trying to keep it + and use the cards to mana fix. You don't really need the lands to pay for the right mana when the card says if it's in your opening hand you may put it into play.
Nykthos, Shrine to Nyx is a nice pseudo-Serra's Sanctum in this deck. If you start the game with multiple Leylines in play you got double the devotion. Get to ramp out Starfield of Nyx on turn two possibly. If you have just two Leylines and 3 lands you can get it out T3 every time.
The other lands I like to run are the Scry lands.
Mainly, Temple of Plenty because they go a long way in helping you send useless Leyline doubles or even triples to the bottom of your deck and bringing up much needed Starfield's or Lands to the top of your deck.
( Also Temple of Enlightenment , Temple of Triumph , Temple of Silence , Temple of Abandon )
Herald of the Pantheon makes everything cheaper. Especially Starfield of the Nyx. Get him out T2 and then on T3 you can possibly play Starfield of Nyx for
Commune with the Gods and Kruphix's Insight sift through the top 5 or 6 cards of your deck and you can grab Starfield of Nyx if you don't have it in your opening hand. Then since the Enchantments are in graveyard once Starfield is put into play you can return them to the battlefield for FREE! This is another way to mana-fix or get around the colors that you don't have. Just get them to graveyard and recur them instead of casting them for their cost and color.
Since you'll fuel your graveyard with a bunch of sorcery and lands through these two cards might as well take advantage and use some Delve cards. Become Immense is the only one that fits in with our color set that's worth using. There's also
Set Adrift
, Temporal Trespass , Dig Through Time , Treasure Cruise ,
Will of the Naga
.
Death Rattle
maybe too, especially if you're playing against any other color than green.
Non-Format / Casual
If you're going pure Casual / non-format then add Serra's Sanctum to ramp mana and play a possible T1 Starfield of Nyx!
Sterling Grove too to go get Starfield and to protect all your Enchantments.
And Exploration too, play more lands each turn and get Starfield out faster.
But then you might as well run with
Opalescence
http://www.gatheringmagic.com/abe-sargent-casual-list-120612-top-10-global-enchantments-of-all-time/