Plains

Leyline of Abundance

If Leyline of Abundance is in your opening hand, you may begin the game with it on the battlefield.
Whenever you tap a creature for mana, add an additional {G}.
{6}{G}{G}: Put a +1/+1 counter on each creature you control.

Wildwood Mentor

Whenever a token you control enters, put a +1/+1 counter on Wildwood Mentor.
Whenever Wildwood Mentor attacks, another target attacking creature gets +X/+X until end of turn, where X is Wildwood Mentor's power.

Call for Unity

Revolt — At the beginning of your end step, if a permanent you controlled left the battlefield this turn, put a unity counter on Call for Unity.
Creatures you control get +1/+1 for each unity counter on Call for Unity.

Rite of Harmony

Whenever a creature or enchantment you control enters this turn, draw a card.
Flashback {2}{G}{W} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Akroma, Vision of Ixidor

Flying, first strike, vigilance, trample
At the beginning of each combat, until end of turn, each other creature you control gets +1/+1 if it has flying, +1/+1 if it has first strike, and so on for double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection, reach, trample, vigilance, and partner.
Partner

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Immaculate Magistrate

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

Eiganjo, Seat of the Empire

{T}: Add {W}.
Channel — {2}{W}, Discard Eiganjo, Seat of the Empire: It deals 4 damage to target attacking or blocking creature. This ability costs {1} less to activate for each legendary creature you control.

Sigarda's Summons

Creatures you control with +1/+1 counters on them have base power and toughness 4/4, have flying, and are Angels in addition to their other types.

Angel's Grace

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
You can't lose the game this turn and your opponents can't win the game this turn. Until end of turn, damage that would reduce your life total to less than 1 reduces it to 1 instead.

Manifold Key

{1}, {T}: Untap another target artifact.
{3}, {T}: Target creature can't be blocked this turn.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Castle Ardenvale

Castle Ardenvale enters tapped unless you control a Plains.
{T}: Add {W}.
{2}{W}{W}, {T}: Create a 1/1 white Human creature token.

Woodland Champion

Whenever one or more tokens you control enter, put that many +1/+1 counters on Woodland Champion.

Noble Purpose

Whenever a creature you control deals combat damage, you gain that much life.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Lys Alana Huntmaster

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

Wolverine Riders

At the beginning of each upkeep, create a 1/1 green Elf Warrior creature token.
Whenever another Elf you control enters, you gain life equal to its toughness.

Tribal Unity

Creatures of the creature type of your choice get +X/+X until end of turn.

Rhys the Redeemed

{2}{G/W}, {T}: Create a 1/1 green and white Elf Warrior creature token.
{4}{G/W}{G/W}, {T}: For each creature token you control, create a token that's a copy of that creature.

Sungrass Prairie

Freyalise, Llanowar's Fury

+2: Create a 1/1 green Elf Druid creature token with "{T}: Add {G}."
−2: Destroy target artifact or enchantment.
−6: Draw a card for each green creature you control.
Freyalise, Llanowar's Fury can be your commander.

Mentor of the Meek

Whenever another creature you control with power 2 or less enters, you may pay {1}. If you do, draw a card.

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Forest

Selvala, Explorer Returned

Parley — {T}: Each player reveals the top card of their library. For each nonland card revealed this way, add {G} and you gain 1 life. Then each player draws a card.

Priest of Titania

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

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Thorn Lieutenant

Whenever Thorn Lieutenant becomes the target of a spell or ability an opponent controls, create a 1/1 green Elf Warrior creature token.
{5}{G}: Thorn Lieutenant gets +4/+4 until end of turn.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Elven Ambush

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

Selesnya Sanctuary

Selesnya Sanctuary enters tapped.
When Selesnya Sanctuary enters, return a land you control to its owner's hand.
{T}: Add {G}{W}.

Unbreakable Formation

Creatures you control gain indestructible until end of turn.
Addendum — If you cast this spell during your main phase, put a +1/+1 counter on each of those creatures and they gain vigilance until end of turn.

Llanowar Tribe

Crown of Skemfar

Enchant creature
Enchanted creature gets +1/+1 for each Elf you control and has reach.
{2}{G}: Return Crown of Skemfar from your graveyard to your hand.

Familiar Ground

Each creature you control can't be blocked by more than one creature.

Voice of the Woods

Tap five untapped Elves you control: Create a 7/7 green Elemental creature token with trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Return to Dust

Exile target artifact or enchantment. If you cast this spell during your main phase, you may exile up to one other target artifact or enchantment.

Magewright's Stone

{1}, {T}: Untap target creature that has an activated ability with {T} in its cost.

Dwynen, Gilt-Leaf Daen

Reach (This creature can block creatures with flying.)
Other Elf creatures you control get +1/+1.
Whenever Dwynen attacks, you gain 1 life for each attacking Elf you control.

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Wirewood Channeler

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

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Incubation Druid

{T}: Add one mana of any type that a land you control could produce. If Incubation Druid has a +1/+1 counter on it, add three mana of that type instead.
{3}{G}{G}: Adapt 3. (If this creature has no +1/+1 counters on it, put three +1/+1 counters on it.)

Realm Seekers

Realm Seekers enters with X +1/+1 counters on it, where X is the total number of cards in all players' hands.
{2}{G}, Remove a +1/+1 counter from Realm Seekers: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Marwyn, the Nurturer

Whenever another Elf you control enters, put a +1/+1 counter on Marwyn, the Nurturer.
{T}: Add an amount of {G} equal to Marwyn's power.

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.

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.

Sol Ring

Puppet Strings

{2}, {T}: You may tap or untap target creature.

Skyshroud Claim

Search your library for up to two Forest cards, put them onto the battlefield, then shuffle.

Snow-Covered Forest

Secret Rendezvous

You and target opponent each draw three cards.

Imperious Perfect

Other Elves you control get +1/+1.
{G}, {T}: Create a 1/1 green Elf Warrior creature token.

Nature's Claim

Destroy target artifact or enchantment. Its controller gains 4 life.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Weatherseed Elf

{T}: Target creature gains forestwalk until end of turn. (It can't be blocked as long as defending player controls a Forest.)

Angelic Exaltation

Whenever a creature you control attacks alone, it gets +X/+X until end of turn, where X is the number of creatures you control.

End-Raze Forerunners

Vigilance, trample, haste
When End-Raze Forerunners enters, other creatures you control get +2/+2 and gain vigilance and trample until end of turn.

Cultivate

Norn's Annex

({W/P} can be paid with either {W} or 2 life.)
Creatures can't attack you or planeswalkers you control unless their controller pays {W/P} for each of those creatures.

Hour of Reckoning

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Destroy all nontoken creatures.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Rishkar, Peema Renegade

When Rishkar, Peema Renegade enters, put a +1/+1 counter on each of up to two target creatures.
Each creature you control with a counter on it has "{T}: Add {G}."

Nyx Lotus

Nyx Lotus enters tapped.
{T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)

Canopy Tactician

Other Elves you control get +1/+1.
{T}: Add {G}{G}{G}.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Elvish Promenade

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.

Elvish Herder

{G}: Target creature gains trample until end of turn.

Bounty of Skemfar

Reveal the top six cards of your library. You may put up to one land card from among them onto the battlefield tapped and up to one Elf card from among them into your hand. Put the rest on the bottom of your library in a random order.

Elvish Archdruid

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