Heartbeat of Spring

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Momentous Fall

As an additional cost to cast this spell, sacrifice a creature.
You draw cards equal to the sacrificed creature's power, then you gain life equal to its toughness.

Traverse the Outlands

Search your library for up to X basic land cards, where X is the greatest power among creatures you control. Put those cards onto the battlefield tapped, then shuffle.

Loxodon Warhammer

Equipped creature gets +3/+0 and has trample and lifelink.
Equip {3}

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

Gelatinous Genesis

Llanowar Tribe

Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Yeva, Nature's Herald

Flash (You may cast this spell any time you could cast an instant.)
You may cast green creature spells as though they had flash.

Beast Whisperer

Whenever you cast a creature spell, draw a card.

Omnath, Locus of Mana

You don't lose unspent green mana as steps and phases end.
Omnath, Locus of Mana gets +1/+1 for each unspent green mana you have.

Nissa, Who Shakes the World

Whenever you tap a Forest for mana, add an additional {G}.
+1: Put three +1/+1 counters on up to one target noncreature land you control. Untap it. It becomes a 0/0 Elemental creature with vigilance and haste that's still a land.
−8: You get an emblem with "Lands you control have indestructible." Search your library for any number of Forest cards, put them onto the battlefield tapped, then shuffle.

Nyxbloom Ancient

Trample
If you tap a permanent for mana, it produces three times as much of that mana instead.

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Giant Ankheg

Trample
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Other creatures you control have trample and ward {2}.

Search for Tomorrow

Search your library for a basic land card, put it onto the battlefield, then shuffle.
Suspend 2—{G} (Rather than cast this card from your hand, you may pay {G} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Vedalken Orrery

You may cast spells as though they had flash.

Mana Reflection

If you tap a permanent for mana, it produces twice as much of that mana instead.