Quirion Ranger

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

Collective Unconscious

Draw a card for each creature you control.

Avoid Fate

Counter target instant or Aura spell that targets a permanent you control.

Priest of Titania

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

Llanowar Elves

Elvish Guidance

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

Fyndhorn Elves

Masticore

At the beginning of your upkeep, sacrifice Masticore unless you discard a card.
{2}: Masticore deals 1 damage to target creature.
{2}: Regenerate Masticore.

Choke

Islands don't untap during their controllers' untap steps.

Timberwatch Elf

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

Sylvan Messenger

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When Sylvan Messenger enters, reveal the top four cards of your library. Put all Elf cards revealed this way into your hand and the rest on the bottom of your library in any order.

Wooded Foothills

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Forest

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.)

Uktabi Orangutan

When Uktabi Orangutan enters, destroy target artifact.

Windswept Heath

{T}, Pay 1 life, Sacrifice Windswept Heath: Search your library for a Forest or Plains card, put it onto the battlefield, then shuffle.

Symbiotic Deployment

Skip your draw step.
{1}, Tap two untapped creatures you control: Draw a card.

Wirewood Pride

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.

Wellwisher

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

Kamahl, Fist of Krosa

{G}: Target land becomes a 1/1 creature until end of turn. It's still a land.
{2}{G}{G}{G}: Creatures you control get +3/+3 and gain trample until end of turn.

Llanowar Sentinel

When Llanowar Sentinel enters, you may pay {1}{G}. If you do, search your library for a card named Llanowar Sentinel, put that card onto the battlefield, then shuffle.