Llanowar Druid

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

Fyndhorn Elves

Gaea's Herald

Llanowar Elves

Taunting Elf

All creatures able to block Taunting Elf do so.

Wirewood Channeler

{T}: Add X mana of any one color, where X is the number of Elves on the battlefield.

Priest of Titania

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

Elvish Soultiller

When Elvish Soultiller dies, choose a creature type. Shuffle all creature cards of that type from your graveyard into your library.

Timberwatch Elf

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

Heedless One

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

Wood Elves

When Wood Elves enters the battlefield, search your library for a Forest card, put that card onto the battlefield, then shuffle.

Elvish Champion

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

Titania's Chosen

Whenever a player casts a green spell, put a +1/+1 counter on Titania's Chosen.

Wirewood Hivemaster

Whenever another nontoken Elf enters the battlefield, you may create a 1/1 green Insect creature token.

Eladamri, Lord of Leaves

Other Elf creatures have forestwalk. (They can't be blocked as long as defending player controls a Forest.)
Other Elves have shroud. (They can't be the targets of spells or abilities.)

Kaysa

Wellwisher

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

Seedtime

Cast this spell only during your turn.
Take an extra turn after this one if an opponent cast a blue spell this turn.