Wirewood Pride

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

Lys Alana Huntmaster

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

Llanowar Druid

{T}, Sacrifice Llanowar Druid: Untap all Forests.

Fyndhorn Elves

Elvish Mystic

You Meet in a Tavern

Choose one —
• Form a Party — Look at the top five cards of your library. You may reveal any number of creature cards from among them and put them into your hand. Put the rest on the bottom of your library in a random order.
• Start a Brawl — Creatures you control get +2/+2 until end of turn.

Forest

Wellwisher

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

Elvish Guidance

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G} for each Elf on the battlefield.

Ethereal Guidance

Creatures you control get +2/+1 until end of turn.

Elvish Vanguard

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

Priest of Titania

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

Llanowar Elves

Timberwatch Elf

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