Guard Patrol Routes

Test Chamber 13: Place portals as shown in the image. Use a portal to move the laser sideways and a time portal to send it into the future. You can take some damage from the laser to travel into the future. Once in the future, rearrange the portals so the laser goes directly into the target.

Test Chamber 14: Travel to the present via a time portal. Summon a reflector cube and position it in the present as shown. Use a portal to bring a laser through the first node and reflect it into the next two nodes. 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. Adjust the present reflector cube to hit all three nodes. Travel back to the future to retrieve the future reflector cube if needed. Place the future reflector cube to reflect the laser into the receiver.

Test Chamber 15: Go 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 reach the future, bypassing the particle field. Head to the other side of the room and use another time portal to return to the present, now on the other side of the particle field. Place a portal on the upper wall to direct the laser to the first receiver. Travel to the future and place a portal on the small wall in the laser room to shoot the receiver. Return to the present. An elevating platform will power up. 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 to the present using a time portal in the laser room. Position it to reflect the laser to the second receiver through the node. To reach the other side of the particle field, use a portal or a time portal. In the present, climb the stairs and use a portal on the upper wall to hit the third receiver. Move the reflector cube onto the switch to complete the chamber.