Follow the now operational robot. Cross the stony bridge and get through a nearby crevice. Follow the pathway, then turn left and climb the stairs. Approach the reel and unlock the door for the robot.
Continue following the robot. You should finally reach a previously visited chamber. The robot will place himself on a special tile, revealing a new figurine. Use your Shout to activate the elevator. Once you've stopped, jump to the platform below and to the shining sphere below you. Picking it up will fill the room with darkness and spawn new shadows.
Approach the field with the shadows and use the sphere to chase them away. The robot will continue moving - follow him. Take the sphere from the room nearby and place it on the pedestal. Follow your companion, then climb on the elevation next to him and start moving through further ledges and column fragments.
You'll finally reach a new chamber. The robot will destroy the thorns, enabling the fox to join the party. Follow both companions to a chamber surrounded by shadows. Use the sphere to chase them off and continue. The shadows will return in a moment - pick up the sphere and jump to the floor below to fend them away.
Keep carrying the sphere and proceed through the dark corridors. Once you've reached your companion, follow him to begin a short cut-scene. Start moving through the flooded corridors to reach a large room that will see you solve a quite complicated riddle.