It might be good to have a bit of a map and a counter of how many batallions I've recruited. I've spent the past hour walking around what appears to now be an empty dungeon and whenever I try to exit, it tells me I'm at 29 of 30. And for the life of me, I can't find the last one.
Edit: of course, just after I posted this comment, I find the last one. Is there more to the story after defeating Darcanos, or is it freeform to get the achievements in the tower?