its to easy XP
just make 3 napols, & send 2 at a time (doesnt matter if they get through, as long as you get the money) then upgrade them all to 2 stars. Start making the most powerful gnomes everywhere and send 2 at a time , but as soon as its almost half-dead, send another to keep it continous. Then just keep making the most powerful gnomes everywhere and you win :P. oh yeah, and make fountains spread out to slow them down. dont upgrade the gnomes neither.