Elvish Vanguard

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

Overrun

Creatures you control get +3/+3 and gain trample until end of turn.

Taunting Elf

All creatures able to block Taunting Elf do so.

Aspect of Mongoose

Enchant creature
Enchanted creature has shroud. (It can't be the target of spells or abilities.)
When Aspect of Mongoose is put into a graveyard from the battlefield, return Aspect of Mongoose to its owner's hand.

Elvish Archers

Might of Old Krosa

Target creature gets +2/+2 until end of turn. If you cast this spell during your main phase, that creature gets +4/+4 until end of turn instead.

Giant Growth

Target creature gets +3/+3 until end of turn.

Timberwatch Elf

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

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.

Titania's Chosen

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

Tribal Forcemage

Morph {1}{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.)
When Tribal Forcemage is turned face up, creatures of the creature type of your choice get +2/+2 and gain trample until end of turn.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Elvish Champion

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

Llanowar Elves

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.

Voice of the Woods

Tap five untapped Elves you control: Create a 7/7 green Elemental creature token with trample.

Gaea's Herald

Everglove Courier

You may choose not to untap Everglove Courier during your untap step.
{2}{G}, {T}: Target Elf creature gets +2/+2 and has trample for as long as Everglove Courier remains tapped.

Wellwisher

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

Blanchwood Armor

Enchant creature
Enchanted creature gets +1/+1 for each Forest you control.

Heedless One

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

Forest

Wirewood Herald

When Wirewood Herald dies, you may search your library for an Elf card, reveal that card, put it into your hand, then shuffle.