On Parade

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 portals without affecting the present. Position portals so the laser goes directly into the target to exit the chamber.

Test Chamber 14: Travel to the present using 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, then use it to reflect the laser 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. If necessary, travel back to the future to retrieve the future reflector cube and bring it to the present again. Finally, position the future reflector cube to reflect the laser into the receiver to complete the chamber.

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 the future to bypass 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 new portal on the upper wall above the laser room to direct the laser to the first receiver. Travel to the future and place a portal in the laser room to shoot at the receiver. Return to the present. An elevating platform near the switch will power up. Stand on it and shoot a time portal behind the node to raise the platform further, allowing you to summon a reflector cube. Place this reflector cube on the lip above the second receiver. Travel to the future. Retrieve the future reflector cube and bring it to the present by placing a time portal in the laser room. Position the cube to reflect the laser to the second receiver through the node. Now, get to the other side of the particle field without going through it (use a portal on the other side or a time portal). 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.