Wirewood Channeler

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

Arbor Elf

Lys Alana Huntmaster

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

Haldir, Lórien Lieutenant

Haldir enters with X +1/+1 counters on it.
Vigilance
{5}{G}: Until end of turn, other Elves you control gain vigilance and get +1/+1 for each +1/+1 counter on Haldir.

Temur Sabertooth

{1}{G}: You may return another creature you control to its owner's hand. If you do, this creature gains indestructible until end of turn.

Priest of Titania

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

Hyrax Tower Scout

When this creature enters, untap target creature.

Animation Module

Whenever one or more +1/+1 counters are put on a permanent you control, you may pay {1}. If you do, create a 1/1 colorless Servo artifact creature token.
{3}, {T}: Choose a counter on target permanent or player. Give that permanent or player another counter of that kind.

Wirewood Symbiote

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

Copperhorn Scout

Whenever this creature attacks, untap each other creature you control.

Yisan, the Wanderer Bard

{2}{G}, {T}, Put a verse counter on Yisan: Search your library for a creature card with mana value equal to the number of verse counters on Yisan, put it onto the battlefield, then shuffle.

Seeker of Skybreak

Quirion Ranger

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

Crown of Skemfar

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

Wellwisher

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