Have

Finale of Devastation

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

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.

Last March of the Ents

This spell can't be countered.
Draw cards equal to the greatest toughness among creatures you control, then put any number of creature cards from your hand onto the battlefield.

Scryb Ranger

Flash
Flying, protection from blue
Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Copperhorn Scout

Whenever Copperhorn Scout attacks, untap each other creature you control.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

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.

Elvish Herder

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

Realmwalker

Changeling (This card is every creature type.)
As Realmwalker enters, choose a creature type.
You may look at the top card of your library any time.
You may cast creature spells of the chosen type from the top of your library.

Essence Warden

Whenever another creature enters, you gain 1 life.

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.)

Vitalize

Wirewood Symbiote

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

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Don't Have

Aluren

Any player may cast creature spells with mana value 3 or less without paying their mana costs and as though they had flash.