User blog comment:B214/Volume 22 spoilers/@comment-14.201.211.143-20160720135918

Here's an idea from what Ravel's true power might be we have only know of two devils who tranform without it being a clan base ability or other power (sacred gear or former race) they are Serzech and Ajuka.

I think she can too and the future super devil's mentioned in Ex can too that might be a super devil is one that has a true form.