Burgeoning

Whenever an opponent plays a land, you may put a land card from your hand onto the battlefield.

Jyoti, Moag Ancient

When Jyoti, Moag Ancient enters, create a 1/1 green Forest Dryad land creature token for each time you've cast your commander from the command zone this game. (They're affected by summoning sickness.)
At the beginning of each combat, land creatures you control get +X/+X until end of turn, where X is Jyoti's power.

Jolrael, Voice of Zhalfir

At the beginning of combat on your turn, up to one target land you control becomes an X/X green and blue Bird creature with flying and haste until end of turn, where X is the number of cards in your hand. It's still a land.
Whenever a land creature you control deals combat damage to a player, draw a card.

Hall of Storm Giants

If you control two or more other lands, Hall of Storm Giants enters tapped.
{T}: Add {U}.
{5}{U}: Until end of turn, Hall of Storm Giants becomes a 7/7 blue Giant creature with ward {3}. It's still a land. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)

Omo, Queen of Vesuva

Whenever Omo, Queen of Vesuva enters or attacks, put an everything counter on each of up to one target land and up to one target creature.
Each land with an everything counter on it is every land type in addition to its other types.
Each nonland creature with an everything counter on it is every creature type.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Mana Reflection

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

Vesuva

You may have Vesuva enter tapped as a copy of any land on the battlefield.

Tatyova, Steward of Tides

Land creatures you control have flying.
Whenever a land you control enters, if you control seven or more lands, up to one target land you control becomes a 3/3 Elemental creature with haste. It's still a land.

Aesi, Tyrant of Gyre Strait

You may play an additional land on each of your turns.
Landfall — Whenever a land you control enters, you may draw a card.

Lumbering Falls

Lumbering Falls enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}: Lumbering Falls becomes a 3/3 green and blue Elemental creature with hexproof until end of turn. It's still a land.

Dryad Arbor

(Dryad Arbor isn't a spell, it's affected by summoning sickness, and it has "{T}: Add {G}.")

Restless Vinestalk

Restless Vinestalk enters tapped.
{T}: Add {G} or {U}.
{3}{G}{U}: Until end of turn, Restless Vinestalk becomes a 5/5 green and blue Plant creature with trample. It's still a land.
Whenever Restless Vinestalk attacks, up to one other target creature has base power and toughness 3/3 until end of turn.

Lair of the Hydra

If you control two or more other lands, Lair of the Hydra enters 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.

Ugin, the Spirit Dragon

+2: Ugin, the Spirit Dragon deals 3 damage to any target.
−X: Exile each permanent with mana value X or less that's one or more colors.
−10: You gain 7 life, draw seven cards, then put up to seven permanent cards from your hand onto the battlefield.