Ferocity of the Wilds

Attacking non-Human creatures you control get +1/+0 and have trample.

Golden Egg

When Golden Egg enters, draw a card.
{1}, {T}, Sacrifice Golden Egg: Add one mana of any color.
{2}, {T}, Sacrifice Golden Egg: You gain 3 life.

Seasonal Ritual

Add one mana of any color. (Then exile this card. You may cast the creature later from exile.)

Rosethorn Acolyte

Rosethorn Acolyte // Seasonal Ritual

Grumgully, the Generous

Each other non-Human creature you control enters with an additional +1/+1 counter on it.

Forest

Legion Warboss

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, create a 1/1 red Goblin creature token. That token gains haste until end of turn and attacks this combat if able.

Witch's Oven

{T}, Sacrifice a creature: Create a Food token. If the sacrificed creature's toughness was 4 or greater, create two Food tokens instead. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Rhythm of the Wild

Creature spells you control can't be countered.
Nontoken creatures you control have riot. (They enter with your choice of a +1/+1 counter or haste.)

Castle Embereth

Castle Embereth enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Fierce Witchstalker

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
When Fierce Witchstalker enters, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Stomping Ground

({T}: Add {R} or {G}.)
As Stomping Ground enters, you may pay 2 life. If you don't, it enters tapped.

Insatiable Appetite

You may sacrifice a Food. If you do, target creature gets +5/+5 until end of turn. Otherwise, that creature gets +3/+3 until end of turn.

Barge In

Target attacking creature gets +2/+2 until end of turn. Each attacking non-Human creature gains trample until end of turn.

Mountain

Feasting Troll King

Vigilance, trample
When Feasting Troll King enters, if you cast it from your hand, create three Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice three Foods: Return Feasting Troll King from your graveyard to the battlefield. Activate only during your turn.