Spitfire Lagac

Landfall — Whenever a land you control enters, Spitfire Lagac deals 1 damage to each opponent.

Akoum Hellhound

Landfall — Whenever a land you control enters, Akoum Hellhound gets +2/+2 until end of turn.

Arachnoform

Enchant creature
Enchanted creature gets +2/+2, has reach, and is every creature type.

Forest

Phylath, World Sculptor

When Phylath, World Sculptor enters, create a 0/1 green Plant creature token for each basic land you control.
Landfall — Whenever a land you control enters, put four +1/+1 counters on target Plant you control.

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

Bramblefort Fink

{8}: Bramblefort Fink has base power and toughness 10/10 until end of turn. Activate only if you control an Oko planeswalker.

Mountain

Canopy Baloth

Landfall — Whenever a land you control enters, Canopy Baloth gets +2/+2 until end of turn.

Territorial Scythecat

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Landfall — Whenever a land you control enters, put a +1/+1 counter on Territorial Scythecat.

Bayou Groff

As an additional cost to cast this spell, sacrifice a creature or pay {3}.

Kazandu Nectarpot

Landfall — Whenever a land you control enters, you gain 1 life.

Skyclave Geopede

Trample
Landfall — Whenever a land you control enters, Skyclave Geopede gets +2/+2 until end of turn.