Vivien of the Arkbow

+2: Put two +1/+1 counters on up to one target creature.
−3: Target creature you control deals damage equal to its power to target creature you don't control.
−9: Creatures you control get +4/+4 and gain trample until end of turn.

Forest

Chitterspitter

At the beginning of your upkeep, you may sacrifice a token. If you do, put an acorn counter on Chitterspitter.
Squirrels you control get +1/+1 for each acorn counter on Chitterspitter.
{G}, {T}: Create a 1/1 green Squirrel creature token.

Haywire Mite

When Haywire Mite dies, you gain 2 life.
{G}, Sacrifice Haywire Mite: Exile target noncreature artifact or noncreature enchantment.

Chatter of the Squirrel

Create a 1/1 green Squirrel creature token.
Flashback {1}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Squirrel Mob

Squirrel Mob gets +1/+1 for each other Squirrel on the battlefield.

Verdant Command

Choose two —
• Target player creates two tapped 1/1 green Squirrel creature tokens.
• Counter target loyalty ability of a planeswalker.
• Exile target card from a graveyard.
• Target player gains 3 life.

Squirrel Sanctuary

When Squirrel Sanctuary enters the battlefield, create a 1/1 green Squirrel creature token.
Whenever a nontoken creature you control dies, you may pay {1}. If you do, return Squirrel Sanctuary to its owner's hand.

Master Symmetrist

Reach
Whenever a creature you control with power equal to its toughness attacks, it gains trample until end of turn.

Harmonious Emergence

Enchant land you control
Enchanted land is a 4/5 green Spirit creature with vigilance and haste. It's still a land.
If enchanted land would be destroyed, instead sacrifice Harmonious Emergence and that land gains indestructible until end of turn.

Master's Rebuke

Target creature you control deals damage equal to its power to target creature or planeswalker you don't control.

Graaz, Unstoppable Juggernaut

Juggernauts you control attack each combat if able.
Juggernauts you control can't be blocked by Walls.
Other creatures you control have base power and toughness 5/3 and are Juggernauts in addition to their other creature types.

Squirrel Sovereign

Prevent all combat damage that would be dealt this turn.

Chatterstorm

Create a 1/1 green Squirrel creature token.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Squirrel Nest

Enchant land
Enchanted land has "{T}: Create a 1/1 green Squirrel creature token."

Scurrid Colony

Reach
Scurrid Colony gets +2/+2 as long as you control eight or more lands.

Naturalize

Chatterfang, Squirrel General

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
If one or more tokens would be created under your control, those tokens plus that many 1/1 green Squirrel creature tokens are created instead.
{B}, Sacrifice X Squirrels: Target creature gets +X/-X until end of turn.