Ozai used an ice blast to scar Zuko. Since Aang is the last earthbender Appa would be the last badgermole after the Earth Kingdom was flooded. Instead of ash, snowfall is the first sign of a Water Tribe attack.
I TAKE ISSUE WITH THAT COMMENT. Of course the Earth Kingdom is trying-Toph's just better than all of them. In my opinion, even Bumi. <--- Bumi has other skills, like not attacking people who annoy him.