When I play modern, I enjoy playing modern elves because I love watching human players despair as I crush their hopes and dreams. With more elf support in GRN, and looking at the best elf deck on tappedout, deck:Elves of Ravnica - (GRN), I was inspired to make my own standard build. And without further ado, on to the card choices.
The team -
Llanowar Elves - OG art of course. A keystone for any elf deck, and turning turn two into turn three is never bad.
Elvish Clancaller - While we don't generate obscene amounts of elves like our modern brother, we do make a quite a few and the ability to tutor an extra lord in the late game (Turn 4 or 5) can really push the game in our favor.
Thorn Lieutenant - Oh you wanted to kill our 2/3 elf that cost two mana? Nice try, he brings a friend just in case.
Steel Leaf Champion - Who doesn't love a degenerate creature that just so happen to also be an elf.
Beast Whisperer - Oh how I wish this was a 1/4 and not a 2/3. The ability to turn basically any of our spells into redraws is a powerful ability if they stick around.
Shalai, Voice of Plenty - Ever since I got her playmat and got it signed at GP DC this last spring, I have been hooked. While she is not an elf Sniffles she deserves to be one. She gives protection to all of our creatures and our own face, (Take that settle!) and can start Gavony Townshiping our team to end the game.
Conclave Guildmage - Don't know how this will work, but in the late game he is a mana sink and he can also give our team trample to help end the game.
Marwyn, the Nurturer - While she starts out weak, with just two played elves she will start to end the game.
Trostani Discordant - Don't piss the plants off. A late game lord that also gives us some life gain tokens (It is at worst a Regal Caracal that isn't a cat.)
Win Conditions -
Swarm Guildmage - What happens when you say that all of your elves have menace? You win the game usually.
Vraska, Golgari Queen - Meh. I don't know if this will work or not but it can give us incidental card draw in the late game, early game removal, and the possibility of winning the game.
March of the Multitudes - While it depresses me that this is a mythic, it is the best of Secure the Wastes and Chord of Calling put together.
Song of Freyalise - I don't know if this is deserves to be in the win condition area or in its own special zone. This limited bomb ramps out your large threats into the possibility of a game winning turn.
Sideboard -
Assassin's Trophy - Hey you. Yeah you. I heard you like removing any problematic threat that your OP plays. If you do, this is the card for you.
Duress - I can see that you are under a lot of pressure, let me just take some of that off of you.
Vivien Reid - She hates people, but hates dragons even more.
Knight of Autumn - This card is impressive from every angle, including card design. R&D was very safe with creature types here, because if they printed this as an elf it would be insanely busted. The ability to outpace aggro, answer artifacts/enchants, or come out as a big body is an impressive skillset.
Shapers' Sanctuary - Turns all of your OP's removal spells into value for you.