Horn of Greed

Whenever a player plays a land, that player draws a card.

Choco-Comet

Choco-Comet deals X damage to any target.
Create a 2/2 green Bird creature token with "Whenever a land you control enters, this token gets +1/+0 until end of turn."

Skyclave Geopede

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

Field of the Dead

This land enters tapped.
{T}: Add {C}.
Whenever this land or another land you control enters, if you control seven or more lands with different names, create a 2/2 black Zombie creature token.

Retreat to Valakut

Landfall — Whenever a land you control enters, choose one —
• Target creature gets +2/+0 until end of turn.
• Target creature can't block this turn.

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 this enchantment, put them into their owner's graveyard, then this enchantment deals that much damage to each opponent.

Tunneling Geopede

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

Sabotender

Reach
Landfall — Whenever a land you control enters, this creature deals 1 damage to each opponent.

Zell Dincht

You may play an additional land on each of your turns.
Zell Dincht gets +1/+0 for each land you control.
At the beginning of your end step, return a land you control to its owner's hand.

Valakut, the Molten Pinnacle

This land enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have this land deal 3 damage to any target.
{T}: Add {R}.