Principal Skinr
Master
I'd ditch the rock salt, and use live rounds, in such a situation. "Ouch!" doesn't carry as much weight as "Omg, theres a 3 inch hole in his chest!"
Oh, I think a bunch of rock salt rapid fire would get the job done. Even in that situation, killing is a last resort. Mobs tend to run from live gun fire. If that fails, though, and they don't, then there's a strategic retreat to a point where the AR comes out. Then, this thing becomes a real disaster. I really don't want to imagine what that looks like.
I still think the Dragon's Breath would put bacon strips in their underwear. Not too many people will run into fire.