Elvish Vanguard

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

Llanowar Elves

Fyndhorn Elves

Nadier's Nightblade

Whenever a token you control leaves the battlefield, each opponent loses 1 life and you gain 1 life.

Wellwisher

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

Elderfang Ritualist

When Elderfang Ritualist dies, return another target Elf card from your graveyard to your hand.

Elrond, Lord of Rivendell

Whenever Elrond, Lord of Rivendell or another creature you control enters, scry 1. If this is the second time this ability has resolved this turn, the Ring tempts you.

Attended Socialite

Alliance — Whenever another creature you control enters, Attended Socialite gets +1/+1 until end of turn.

Dionus, Elvish Archdruid

Elves you control have "Whenever this creature becomes tapped during your turn, untap it and put a +1/+1 counter on it. This ability triggers only once each turn."

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.)

Elderfang Disciple

When Elderfang Disciple enters, each opponent discards a card.

Jagged-Scar Archers

Jagged-Scar Archers's power and toughness are each equal to the number of Elves you control.
{T}: Jagged-Scar Archers deals damage equal to its power to target creature with flying.

Thornmantle Striker

When Thornmantle Striker enters, choose one —
• Remove X counters from target permanent, where X is the number of Elves you control.
• Target creature an opponent controls gets -X/-X until end of turn, where X is the number of Elves you control.

Essence Warden

Whenever another creature enters, you gain 1 life.

Nettle Sentinel

Nettle Sentinel doesn't untap during your untap step.
Whenever you cast a green spell, you may untap Nettle Sentinel.

Jaspera Sentinel

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

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Galadhrim Brigade

Squad {1}{G} (As an additional cost to cast this spell, you may pay {1}{G} any number of times. When this creature enters, create that many tokens that are copies of it.)
Other Elves you control get +1/+1.

Abomination of Llanowar

Vigilance; menace (This creature can't be blocked except by two or more creatures.)
Abomination of Llanowar's power and toughness are each equal to the number of Elves you control plus the number of Elf cards in your graveyard.

Forest

Taunting Elf

All creatures able to block Taunting Elf do so.

Frilled Mystic

Flash
When Frilled Mystic enters, you may counter target spell.

Elderfang Venom

Attacking Elves you control have deathtouch.
Whenever an Elf you control dies, each opponent loses 1 life and you gain 1 life.

Elvish Promenade

Create a 1/1 green Elf Warrior creature token for each Elf you control.

Elvish Harbinger

When Elvish Harbinger enters, you may search your library for an Elf card, reveal it, then shuffle and put that card on top.
{T}: Add one mana of any color.

Devoted Druid

{T}: Add {G}.
Put a -1/-1 counter on Devoted Druid: Untap Devoted Druid.

Priest of Titania

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

Decorated Champion

Whenever another Warrior your team controls enters, put a +1/+1 counter on Decorated Champion.

Immaculate Magistrate

{T}: Put a +1/+1 counter on target creature for each Elf you control.

Timberwatch Elf

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

Tyvar Kell

Elves you control have "{T}: Add {B}."
+1: Put a +1/+1 counter on up to one target Elf. Untap it. It gains deathtouch until end of turn.
0: Create a 1/1 green Elf Warrior creature token.
−6: You get an emblem with "Whenever you cast an Elf spell, it gains haste until end of turn and you draw two cards."

Drove of Elves

Hexproof
Drove of Elves's power and toughness are each equal to the number of green permanents you control.

Heritage Druid

Tap three untapped Elves you control: Add {G}{G}{G}.

Elvish Visionary

When Elvish Visionary enters, draw a card.

Eyeblight's Ending

Quirion Ranger

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

Lys Alana Scarblade

{T}, Discard an Elf card: Target creature gets -X/-X until end of turn, where X is the number of Elves you control.

Fauna Shaman

{G}, {T}, Discard a creature card: Search your library for a creature card, reveal it, put it into your hand, then shuffle.

Leaf-Crowned Visionary

Other Elves you control get +1/+1.
Whenever you cast an Elf spell, you may pay {G}. If you do, draw a card.

Jarad, Golgari Lich Lord

Jarad, Golgari Lich Lord gets +1/+1 for each creature card in your graveyard.
{1}{B}{G}, Sacrifice another creature: Each opponent loses life equal to the sacrificed creature's power.
Sacrifice a Swamp and a Forest: Return Jarad from your graveyard to your hand.

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Shaman of the Pack

When Shaman of the Pack enters, target opponent loses life equal to the number of Elves you control.

Wirewood Pride

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

Swamp

Elvish Mystic

Heedless One

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

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.)