I love a good Land Destruction deck, and recently played a Modern version at GP Vancouver. I like your build a lot (though I imagine your friends may not be big fans), and was wondering if you had considered
Avalanche Riders. Since they have Haste, you can pretty much always get in for 2, and if you have nothing else to do the following turn, paying the echo isn't too bad since it lets you keep beating down.
Another sweet option is
goblin Dark-Dwellers. a 4/4/ menace
ends games fast, and getting back a
pillage or
molten rain for free puts you that much further ahead.
Hope this gives you some ideas! Good luck