Scurry Oak

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever one or more +1/+1 counters are put on Scurry Oak, you may create a 1/1 green Squirrel creature token.

Forest

Chameleon Colossus

Changeling (This card is every creature type.)
Protection from black
{2}{G}{G}: Chameleon Colossus gets +X/+X until end of turn, where X is its power.

Nested Shambler

When Nested Shambler dies, create X tapped 1/1 green Squirrel creature tokens, where X is Nested Shambler's power.

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.

Webweaver Changeling

Changeling (This card is every creature type.)
Reach
When Webweaver Changeling enters, if there are three or more creature cards in your graveyard, you gain 5 life.

Might of the Masses

Target creature gets +1/+1 until end of turn for each creature you control.

Swamp

Squirrel Sovereign

Ravenous Squirrel

Whenever you sacrifice an artifact or creature, put a +1/+1 counter on Ravenous Squirrel.
{1}{B}{G}, Sacrifice an artifact or creature: You gain 1 life and draw a card.

Drey Keeper

When Drey Keeper enters, create two 1/1 green Squirrel creature tokens.
{3}{B}: Squirrels you control get +1/+0 and gain menace until end of turn.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Destroy target creature.

Jungle Hollow

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {G}.

Bone Shards

As an additional cost to cast this spell, sacrifice a creature or discard a card.
Destroy target creature or planeswalker.