There is another thread for this deck out there somewhere (maybe another site). Anyhow they are using Vesuva x 4 to copy either Valakut or Mountain.

Some card you may wish to consider (depending on build);

Lightning Bolt
Crop Rotation
Countryside Crusher? with Loam build and flashback cards
Conflagrate (RR for 5-7? counter productive with Manabond)
Deep Recon
Firebolt
Krosan Reclamation
Lava Dart
Lightning Surge
Volley of Boulders

Ancient Grudge (sideboard)

I know alot of those cards are downright awful but as 1-offs in a dredge style deck, they could push through the last few points of damage from the graveyard.