Now get to the floor of the bronze basin under you. To get there, follow the ramps down and back outside. Take a path to the right that drops down and hugs the side of tthe cliff edge. Follow it round and up until you emerge under the chain you travelled along earlier. Keep going forward, then to the left, and up the stairs. This area will open up into a "temple" of sorts. Take the path on the left, and see the Polyarch skeleton. Keep going straight, and through the portal at the end of this path. Keep going along this new path and up the stairs. Off one of the landings as the stairs zigzag up is a room with the new seed-swap device, going to Maray.
You'll come out above the white door we saw earlier, except this time, you have a panel to interact with.
Connect the last corner, and hit the button. Return using the seed-swap device.