There isn't one (which I assume is a spoiler in and of itself, hence the tag). I'll admit that is kind of surprising (and disappointing). Jaina just teleports out at low HP and that is that. Just ENOUGHs away.
Just thought you'd want to know. Kind of weird to not have one, likely will make the final fight a lot more dissatisfying. YMMV, I don't raid anymore.