Slaughter the Strong

Each player chooses any number of creatures they control with total power 4 or less, then sacrifices all other creatures they control.

Awakener Druid

When Awakener Druid enters, target Forest becomes a 4/5 green Treefolk creature for as long as Awakener Druid remains on the battlefield. It's still a land.

Wave of Reckoning

Each creature deals damage to itself equal to its power.

Fell the Mighty

Destroy all creatures with power greater than target creature's power.

Living Terrain

Enchant land
Enchanted land is a 5/6 green Treefolk creature that's still a land.

Rootgrapple

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

Bog-Strider Ash

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Whenever a player casts a Goblin spell, you may pay {G}. If you do, you gain 2 life.

Murmuring Bosk

({T}: Add {G}.)
As Murmuring Bosk enters, you may reveal a Treefolk card from your hand. If you don't, Murmuring Bosk enters tapped.
{T}: Add {W} or {B}. Murmuring Bosk deals 1 damage to you.

Dawn

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Return all creature cards with power 2 or less from your graveyard to your hand.

Dusk

Destroy all creatures with power 3 or greater.

Dusk // Dawn

Huatli, the Sun's Heart

Each creature you control assigns combat damage equal to its toughness rather than its power.
−3: You gain life equal to the greatest toughness among creatures you control.

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.

Ancient of the Equinox

Autumnal Gloom

{B}: Mill a card.
Delirium — At the beginning of your end step, if there are four or more card types among cards in your graveyard, transform Autumnal Gloom.

Autumnal Gloom // Ancient of the Equinox

Bosk Banneret

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

Faeburrow Elder

Vigilance
Faeburrow Elder gets +1/+1 for each color among permanents you control.
{T}: For each color among permanents you control, add one mana of that color.

Sapling of Colfenor

Indestructible
Whenever Sapling of Colfenor attacks, reveal the top card of your library. If it's a creature card, you gain life equal to that card's toughness, lose life equal to its power, then put it into your hand.

Deadwood Treefolk

Vanishing 3 (This creature enters with three time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When Deadwood Treefolk enters or leaves the battlefield, return another target creature card from your graveyard to your hand.

Timber Protector

Other Treefolk creatures you control get +1/+1.
Other Treefolk and Forests you control have indestructible.

Black Poplar Shaman

Reach of Branches

Create a 2/5 green Treefolk Shaman creature token.
Whenever a Forest you control enters, you may return Reach of Branches from your graveyard to your hand.

Behind the Scenes

Creatures you control have skulk. (They can't be blocked by creatures with greater power.)
{4}{W}: Creatures you control get +1/+1 until end of turn.

Lignify

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

Magnigoth Treefolk

Domain — For each basic land type among lands you control, Magnigoth Treefolk has landwalk of that type. (It can't be blocked as long as defending player controls a land of that type.)

Doran, the Siege Tower

Each creature assigns combat damage equal to its toughness rather than its power.

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.