Ghalta, Primal Hunger

This spell costs {X} less to cast, where X is the total power of creatures you control.
Trample

Scavenging Ooze

{G}: Exile target card from a graveyard. If it was a creature card, put a +1/+1 counter on Scavenging Ooze and you gain 1 life.

Llanowar Visionary

When Llanowar Visionary enters, draw a card.
{T}: Add {G}.

Aggressive Mammoth

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Other creatures you control have trample.

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Forest

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Great Oak Guardian

Flash (You may cast this spell any time you could cast an instant.)
Reach
When Great Oak Guardian enters, creatures target player controls get +2/+2 until end of turn. Untap them.

Genesis Wave

Reveal the top X cards of your library. You may put any number of permanent cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield into your graveyard.

Pelakka Wurm

Trample
When Pelakka Wurm enters, you gain 7 life.
When Pelakka Wurm dies, draw a card.

Thorn Mammoth

Trample
Whenever Thorn Mammoth or another creature you control enters, Thorn Mammoth fights up to one target creature you don't control.

Arbor Elf

Ripjaw Raptor

Enrage — Whenever Ripjaw Raptor is dealt damage, draw a card.

Primal Might

Target creature you control gets +X/+X until end of turn. Then it fights up to one target creature you don't control.

Tail Swipe

Choose target creature you control and target creature you don't control. If you cast this spell during your main phase, the creature you control gets +1/+1 until end of turn. Then those creatures fight each other. (Each deals damage equal to its power to the other.)

Abundant Harvest

Choose land or nonland. Reveal cards from the top of your library until you reveal a card of the chosen kind. Put that card into your hand and the rest on the bottom of your library in a random order.