Acorn Harvest

Create two 1/1 green Squirrel creature tokens.
Flashback—{1}{G}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Giant Growth

Target creature gets +3/+3 until end of turn.

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When this Aura is put into a graveyard from the battlefield, return it to its owner's hand.

Llanowar Elves

Generous Ent

Reach
When this creature enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Forestcycling {1} ({1}, Discard this card: Search your library for a Forest card, reveal it, put it into your hand, then shuffle.)

Tangle Golem

Affinity for Forests (This spell costs {1} less to cast for each Forest you control.)

Ulamog's Crusher

Annihilator 2 (Whenever this creature attacks, defending player sacrifices two permanents of their choice.)
This creature attacks each combat if able.

Poison the Blade

Target creature gains deathtouch until end of turn.
Draw a card.

Owlbear

Trample
Keen Senses — When this creature enters, draw a card.

Forest

Predator's Rapport

Choose target creature you control. You gain life equal to that creature's power plus its toughness.

Gingerbrute

Haste (This creature can attack and {T} as soon as it comes under your control.)
{1}: This creature can't be blocked this turn except by creatures with haste.
{2}, {T}, Sacrifice this creature: You gain 3 life.