Chernobog

Test Chamber 13: Place portals as shown in the image to redirect the laser. Use a time portal to move the laser into the future. Enter the time portal yourself, potentially taking damage, to reach the future. In the future, rearrange portals to direct the laser into the target, then exit through the door.

Test Chamber 14: First, travel to the present using a time portal. Summon a reflector cube and position it in the present as indicated. Use a portal to direct a laser through the first node and then 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 via a time portal. Ensure the present reflector cube hits all three nodes; adjust as needed. If you moved the future reflector cube, return to the future to retrieve it again. Finally, place the future reflector cube at the end of the nodes to reflect the laser into the receiver, completing the chamber.

Test Chamber 15: Begin by passing 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 particle field. Place a new portal on the upper wall to direct the laser to the first receiver. Travel back to the future and place a portal on the small wall in the laser room to aim at the receiver. Return to the present; the laser should be hitting the first receiver, powering an elevating platform. Stand on this platform and place 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 and retrieve the future reflector cube. Return to the present by placing a time portal in the laser room. Position the future reflector cube to reflect the laser into the second receiver through the node. To reach the other side of the particle field without passing through it, use an existing portal or a time portal. You need to be 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.