Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Llanowar Elves

Elvish Champion

Other Elf creatures get +1/+1 and have forestwalk. (They can't be blocked as long as defending player controls a Forest.)

Heedless One

Trample
Heedless One's power and toughness are each equal to the number of Elves on the battlefield.

Elvish Promenade

Create a 1/1 green Elf Warrior creature token for each Elf you control.

Canopy Tactician

Other Elves you control get +1/+1.
{T}: Add {G}{G}{G}.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Lys Alana Huntmaster

Whenever you cast an Elf spell, you may create a 1/1 green Elf Warrior creature token.

Realmwalker

Changeling (This card is every creature type.)
As this creature enters, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Oracle of Mul Daya

You may play an additional land on each of your turns.
Play with the top card of your library revealed.
You may play lands from the top of your library.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Elvish Warmaster

Whenever one or more other Elves you control enter, create a 1/1 green Elf Warrior creature token. This ability triggers only once each turn.
{5}{G}{G}: Elves you control get +2/+2 and gain deathtouch until end of turn.