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.

Advocate of the Beast

At the beginning of your end step, put a +1/+1 counter on target Beast creature you control.

Forest

Elder Gargaroth

Vigilance, reach, trample
Whenever Elder Gargaroth attacks or blocks, choose one —
• Create a 3/3 green Beast creature token.
• You gain 3 life.
• Draw a card.

Herd Baloth

Whenever one or more +1/+1 counters are put on Herd Baloth, you may create a 4/4 green Beast creature token.

Keeper of the Beasts

{G}, {T}: Choose target opponent who controls more creatures than you do as you activate this ability. Create a 2/2 green Beast creature token.

Plains

Mountain

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Somberwald Beastmaster

When Somberwald Beastmaster enters, create a 2/2 green Wolf creature token, a 3/3 green Beast creature token, and a 4/4 green Beast creature token.
Creature tokens you control have deathtouch.

Beast Attack

Create a 4/4 green Beast creature token.
Flashback {2}{G}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Leery Fogbeast

Whenever Leery Fogbeast becomes blocked, prevent all combat damage that would be dealt this turn.

Krosan Warchief

Beast spells you cast cost {1} less to cast.
{1}{G}: Regenerate target Beast.

Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.