Forest

Mountain

Stomping Ground

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

Ashaya, Soul of the Wild

Ashaya, Soul of the Wild's power and toughness are each equal to the number of lands you control.
Nontoken creatures you control are Forest lands in addition to their other types. (They're still affected by summoning sickness.)

Dryad of the Ilysian Grove

You may play an additional land on each of your turns.
Lands you control are every basic land type in addition to their other types.

Experimental Frenzy

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library.
You can't play lands or cast spells from your hand.
{3}{R}: Destroy Experimental Frenzy.

Oracle of Mul Daya

You may play an additional land on each of your turns.
Play with the top card of your library revealed.
You may play lands from the top of your library.

Lotus Cobra

Landfall — Whenever a land you control enters, add one mana of any color.

Azusa, Lost but Seeking

You may play two additional lands on each of your turns.

Ancient Greenwarden

Reach (This creature can block creatures with flying.)
You may play lands from your graveyard.
If a land entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Evolving Wilds

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Valakut Exploration

Landfall — Whenever a land you control enters, exile the top card of your library. You may play that card for as long as it remains exiled.
At the beginning of your end step, if there are cards exiled with Valakut Exploration, put them into their owner's graveyard, then Valakut Exploration deals that much damage to each opponent.

Druid Class

(Gain the next level as a sorcery to add its ability.)
Landfall — Whenever a land you control enters, you gain 1 life.
{2}{G}: Level 2
You may play an additional land on each of your turns.
{4}{G}: Level 3
When this Class becomes level 3, target land you control becomes a creature with haste and "This creature's power and toughness are each equal to the number of lands you control." It's still a land.