Foundry may just have the most amazing terraforming tool I've encountered in a destructible voxel terrain game: an orbital laser cannon. It's not exactly a precision instrument, but it's highly effective at removing inconvenient mountain ranges, and extremely satisfying to use. Minecraft needs one.
Oh shit, I'm planning a space mod anyway. I can add my own orbital laser cannon!
But yeah, I'm pretty sure I know how I'd implement it technically. The hard part would be making it look and sound right. Foundry does a good job on that front, too. Pew pew!