Timberwatch Elf

{T}: Target creature gets +X/+X until end of turn, where X is the number of Elves on the battlefield.

Llanowar Elves

Elvish Vanguard

Whenever another Elf enters, put a +1/+1 counter on Elvish Vanguard.

Lead the Stampede

Look at the top five cards of your library. You may reveal any number of creature cards from among them and put the revealed cards into your hand. Put the rest on the bottom of your library in any order.

Quirion Ranger

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Birchlore Rangers

Tap two untapped Elves you control: Add one mana of any color.
Morph {G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Priest of Titania

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

Fyndhorn Elves

Forest

Lys Alana Huntmaster

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

Jaspera Sentinel

Reach
{T}, Tap an untapped creature you control: Add one mana of any color.

Essence Warden

Whenever another creature enters, you gain 1 life.

Elvish Mystic

Wellwisher

{T}: You gain 1 life for each Elf on the battlefield.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.