Apparently she appears from one of the sides in the arena and marks someone.

After she casts Divebomb, she will rush into the marked person and turn (I think it's to her right, but I'm not sure). I believe the reason we all go into the pit and just run up and down is because her spawn points are limited, making the pit the only safe place to do this strategy. I am absolutely not sure if this is how it works or not, just how I see it.