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.)

Arbor Elf

Imperious Perfect

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

Joraga Treespeaker

Level up {1}{G} ({1}{G}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-4
1/2
{T}: Add {G}{G}.
LEVEL 5+
1/4
Elves you control have "{T}: Add {G}{G}."

Elvish Champion

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

Elvish Mystic

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.

Birds of Paradise

Forest

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}."

Dwynen, Gilt-Leaf Daen

Reach
Other Elf creatures you control get +1/+1.
Whenever Dwynen, Gilt-Leaf Daen attacks, you gain 1 life for each attacking Elf you control.

Karametra's Acolyte

{T}: Add an amount of {G} equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

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.

Fyndhorn Elves

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.

Circle of Dreams Druid

{T}: Add {G} for each creature you control.

Wirewood Channeler

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

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.

Joraga Warcaller

Multikicker {1}{G} (You may pay an additional {1}{G} any number of times as you cast this spell.)
Joraga Warcaller enters with a +1/+1 counter on it for each time it was kicked.
Other Elf creatures you control get +1/+1 for each +1/+1 counter on Joraga Warcaller.

Canopy Tactician

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

Llanowar Elves

Llanowar Visionary

When Llanowar Visionary enters, draw a card.
{T}: Add {G}.

Llanowar Tribe

Sylvan Anthem

Green creatures you control get +1/+1.
Whenever a green creature you control enters, scry 1.

Priest of Titania

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

Boreal Druid

Elvish Archdruid

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