Wirewood Symbiote

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

Reclamation Sage

When Reclamation Sage enters, you may destroy target artifact or enchantment.

Llanowar Scout

{T}: You may put a land card from your hand onto the battlefield.

Copperhorn Scout

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

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.

Yisan, the Wanderer Bard

{2}{G}, {T}, Put a verse counter on Yisan, the Wanderer Bard: 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.

Acidic Slime

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
When Acidic Slime enters, destroy target artifact, enchantment, or land.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Regal Force

When Regal Force enters, draw a card for each green creature you control.

Llanowar Tribe

Forest

Arbor Elf

Seeker of Skybreak

Fertilid

Fertilid enters with two +1/+1 counters on it.
{1}{G}, Remove a +1/+1 counter from Fertilid: Target player searches their library for a basic land card, puts it onto the battlefield tapped, then shuffles.

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.)

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)