Mogul

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, potentially taking some damage. Rearrange portals in the future to direct the laser into the target, then proceed through the exit door.

Test Chamber 14: Travel to the present via 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, 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. Position the present reflector cube to hit all three nodes; adjust as needed. Return to the future if the cube was moved. Place the future reflector cube at the end of the nodes to reflect the laser into the receiver, completing 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. 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 above the laser room to direct the laser to the first receiver. Travel back to the future and place a portal in the laser room to shoot the receiver. Return to the present. The laser should power up 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 via 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 passing through it, use a portal on the other side 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.