DC20(Modern): Landslide

Surely there is a landfall card that does damage to player or something that could add a win element to that combo.

Well let's have a look here...*rummage rummage rummage*
As a matter of fact, we DO!
Ob Nixilis, the Fallen can drain 3 life per land.
Cosi's Ravager can deal one damage per.
If you don't want to use Amulet of Vigor, you could use the potent Lotus Cobra.
Heck if you just threw Perilous Forays into Zendikar, the whole plane would burst with awesomeness. Sometimes I have to let you kids discover things for yourselves. 😌

Edit: oh yeah, and don't call me Shirely. 😜

For some old-school good times, you could dust of the ol' Charbelcher.