Kazandu Nectarpot

Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.

Fertile Footsteps

Search your library for a basic land card, put it onto the battlefield, then shuffle. (Then exile this card. You may cast the creature later from exile.)

Beanstalk Giant

Beanstalk Giant's power and toughness are each equal to the number of lands you control.

Beanstalk Giant // Fertile Footsteps

Generated Horizons

At the beginning of your upkeep, create a Forest land token.

Canopy Baloth

Landfall — Whenever a land enters the battlefield under your control, Canopy Baloth gets +2/+2 until end of turn.

Forest

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Yavimaya Dryad

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
When Yavimaya Dryad enters the battlefield, you may search your library for a Forest card, put it onto the battlefield tapped under target player's control, then shuffle.

Broken Bond

Destroy target artifact or enchantment. You may put a land card from your hand onto the battlefield.

Arboreal Grazer

Reach
When Arboreal Grazer enters the battlefield, you may put a land card from your hand onto the battlefield tapped.

Horizon Seeker

Boast — {1}{G}: Search your library for a basic land card, reveal it, put it into your hand, then shuffle. (Activate only if this creature attacked this turn and only once each turn.)

Enter the Unknown

Target creature you control explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on the creature, then put the card back or put it into your graveyard.)
You may play an additional land this turn.

Jaddi Offshoot

Defender
Landfall — Whenever a land enters the battlefield under your control, you gain 1 life.

Undergrowth Champion

If damage would be dealt to Undergrowth Champion while it has a +1/+1 counter on it, prevent that damage and remove a +1/+1 counter from Undergrowth Champion.
Landfall — Whenever a land enters the battlefield under your control, put a +1/+1 counter on Undergrowth Champion.

Lair of the Hydra

If you control two or more other lands, Lair of the Hydra enters the battlefield tapped.
{T}: Add {G}.
{X}{G}: Until end of turn, Lair of the Hydra becomes an X/X green Hydra creature. It's still a land. X can't be 0.

Thriving Grove

Thriving Grove enters the battlefield tapped.
As Thriving Grove enters the battlefield, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.