Omnath, Locus of Creation

When Omnath enters, draw a card.
Landfall — Whenever a land you control enters, you gain 4 life if this is the first time this ability has resolved this turn. If it's the second time, add {R}{G}{W}{U}. If it's the third time, Omnath deals 4 damage to each opponent and each planeswalker you don't control.

Lotus Cobra

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

Ashaya, Soul of the Wild

Ashaya'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.

Sol Ring

Annie Joins Up

When Annie Joins Up enters, it deals 5 damage to target creature or planeswalker an opponent controls.
If a triggered ability of a legendary creature you control triggers, that ability triggers an additional time.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Birds of Paradise

Bloom Tender

Vivid — {T}: For each color among permanents you control, add one mana of that color.

Azusa, Lost but Seeking

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

Avenger of Zendikar

When this creature enters, create a 0/1 green Plant creature token for each land you control.
Landfall — Whenever a land you control enters, you may put a +1/+1 counter on each Plant creature you control.