Venture To The Sewers

Test Chamber 13: Place portals as shown to redirect the laser. Use a time portal to move the laser into the future, then enter the time portal yourself. Once in the future, rearrange portals to direct the laser into the target and exit the chamber.

Test Chamber 14: Travel to the present via a time portal. Summon a reflector cube and position it as shown. Use portals to direct a laser through the first node, then reflect it into the next two. Travel to the future. Use portals to bring a laser into the present through the time portal, ensuring it passes through the node. Retrieve the reflector cube from the future and bring it to the present. Position the present reflector cube to hit all three nodes. If necessary, return to the future to retrieve the future reflector cube again and bring it to the present. Finally, place the future reflector cube to reflect the laser into the receiver, completing the chamber.

Test Chamber 15: Start by going through the particle field to the left. Place a portal where the laser hits the wall and a time portal on the opposite wall. Travel through the time portal to the future to bypass the particle field. Proceed to the other side of the room and use another time portal to return to the present, now on the other side of the field. Place a new portal on the upper wall so the laser hits the first receiver. Return to the future and place a portal on the small wall in the laser room to shoot the receiver. Return to the present. The laser should now power an elevating platform. Stand on it and place a time portal behind the node to raise the platform further, allowing you to summon a reflector cube. Place this cube on the lip above the second receiver. Travel to the future. Retrieve the future reflector cube and bring it back to the present using a time portal in the laser room. Position it to reflect the laser into the second receiver through the node. To reach the other side of the particle field without going through it, use an existing portal or a time portal. Once in the present on the other side, climb the stairs and use a portal on the upper wall to hit the third receiver. Finally, move the reflector cube onto the switch to complete the chamber.