YA Fantasy

I read a book about a school for wizards. They had an ogre named Bob and a hag as cooks. The hags sister came to stay with her and had haglets. One of the most powerful students got his arm bitten off by the "bad guy". There was a gigantic black cat and an animal similar to an armadillo that ate metal. They fought a cyclops. Does anyone know the name of this book? I think it was the first of a series. It is a pretty new book.

I'm pretty sure it's The Hound of Rowan or another in the Tapestry series

Rubbah, that is it! Thank you very much. I recognize the cover.