Huh. Well, from the Mu that I have been fighting so far, all the matches are just me IBing bullets until I get about 30 Heat, jumping over the Guard Primer taking ones, then using whatever arching command special to get close. Those bullets move really slow so, seeing them isn't something tough at all. Her DP, seems like it stops cross overs and with how close ragna likes to be, it's a good tool. Also, Counter Assault, Because most Ragna's don't pay attn to such, are always good.
She's new. No one knows anything pretty much. :/
So far, with how early it is, I don't see Ragna having a problem with her, unless Mu is doing a lot of IB into her DP. In which case, there are going to be a lot of Jump Canceling of normals going on to cross up that DP attempt. As more people play her though and her normals get figure'd out more, we'll see something more deadly.
Now, if she had some moves at gave her foot invincibility, we'd see a bit more of a fight. Being that a good chuck of Ragna's blockstring normals are foot attribute only, she could have a way out besides DPing all the time. She wouldn't have to mess with 2[anything] from him.