Ambassador Oak

When Ambassador Oak enters, create a 1/1 green Elf Warrior creature token.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Ulvenwald Observer

Whenever a creature you control with toughness 4 or greater dies, draw a card.

Descendants' Path

At the beginning of your upkeep, reveal the top card of your library. If it's a creature card that shares a creature type with a creature you control, you may cast it without paying its mana cost. If you don't cast it, put it on the bottom of your library.

Arbor Elf

Ghoultree

This spell costs {1} less to cast for each creature card in your graveyard.

Rootgrapple

Destroy target noncreature permanent. If you control a Treefolk, draw a card.

Invigorate

If you control a Forest, rather than pay this spell's mana cost, you may have an opponent gain 3 life.
Target creature gets +4/+4 until end of turn.

Llanowar Tribe

Snare the Skies

Target creature gets +1/+1 and gains reach until end of turn. (It can block creatures with flying.)

Nissa's Triumph

Search your library for up to two basic Forest cards. If you control a Nissa planeswalker, instead search your library for up to three land cards. Reveal those cards, put them into your hand, then shuffle.

Kalonian Twingrove

Kalonian Twingrove's power and toughness are each equal to the number of Forests you control.
When Kalonian Twingrove enters, create a green Treefolk Warrior creature token with "This creature's power and toughness are each equal to the number of Forests you control."

Whirlwind

Bosk Banneret

Treefolk spells and Shaman spells you cast cost {1} less to cast.

Treefolk Harbinger

When Treefolk Harbinger enters, you may search your library for a Treefolk or Forest card, reveal it, then shuffle and put that card on top.

Orchard Warden

Whenever another Treefolk creature you control enters, you may gain life equal to that creature's toughness.

Lignify

Enchant creature
Enchanted creature is a Treefolk with base power and toughness 0/4 and loses all abilities.

Gnarled Professor

Trample
When Gnarled Professor enters, learn. (You may reveal a Lesson card you own from outside the game and put it into your hand, or discard a card to draw a card.)

Forest

Dauntless Dourbark

Dauntless Dourbark's power and toughness are each equal to the number of Forests you control plus the number of Treefolk you control.
Dauntless Dourbark has trample as long as you control another Treefolk.

Crashing Footfalls

Suspend 4—{G} (Rather than cast this card from your hand, pay {G} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Create two 4/4 green Rhino creature tokens with trample.