there's a door at the south so you won't be able to go through. it's probably the 7 Sou Warp area, where the boss is.
there's a small room at southeast and northwest, Archaic Rampart will appear one each. that door will call Greater Manticore which are very strong.
north of the big area there is a Chariot. if you fish it, then Archaic Gears multiply by 10 and Archaic gears appear all over. if you use some magic to change you (sneak?), you can pull the tank without pulling the rest of the monsters.
we are still searching for how to get to the 7 Sou. but it definitely seems like you have to beat the 5th and 6th Sou chariot NM. in addition, you need to break both NM's doors.
yet, someone hash reported that if you beat all 12 gears that pop and the chariot, the door will open. people are still searching to figure it out but it's still not fully determined.