You literally transmute matter at will, you do not need to fight Killcannon just turn his robot arm into cheese or something. Your nemesis is a villain that you do not need to consider the whole cannot effect living tissue thing for even a second. That is all.
At the very least she should easily incapacitate any armored threats, possibly non-flying threats (turn ground into quicksand sort of deal) besides some really powerful ones. A beast (like Hail Mary or something like Rognarrs) would pose a lot of problems for her though.