Since it is just out the back of the prison, it might be best for her to close it before Xavier can follow. Give you all a bit more of a headstart. I'm still not sure how the little chase scene should end though, perhaps Elisa uses some non-fatal magic on Xavier.
On the other hand, if the doorway led to say the dark forest, we could all be in front of the Valravn in a couple of posts. I'm good either way though, and even with other options I haven't even considered yet.