All he has do is not miss plus had has ability to upgrade his skills beyond limit and stack and he can just have his slime dragon evolved just eat her lol also increase gravity
The way to beat absolute avoidance of attacks is use transportation magic on wide area. It's not an attack, and it cant be avoided. A nice trip above the ocean perhaps?
If all her skill does is turn all opponent accuracy check into zero, and thus miss. There's honestly many ways to deal with it.
But I doubt its just that. Lets wait and see what else she's got, as the former Hero.