Monolith location for chapter 3.
Location of Monolith in Chapter 3
You must finish chapter 3 and chapter 8.
Solve the puzzle on the last level (MIMBLA in break the loop) and press the button.
Wander around when you find this room.
Go to chapter 8, warp to layer 2.
Go back to chapter 3 and enter through the karma portal. Enjoy!