Head to the console ahead and activate it for a scene. After that, enter the portal. Follow the path and engage the new enemies coming out from the walls. Aim for their head to kill them quickly. Activate the light bridge ahead then continue forth. You'll be jumped on by one of those new humanoid enemies you encountered earlier. After that, move on until you reach a large, open area. More enemies will attack so stand your ground and eliminate them. Take note that you have a shield ability equipped, which will enable you to briefly block any enemy attack. Use this to get closer to the Promethean Knight and its drone.
Head inside the building and grab some new weapons using the weapon caches along the way. Exit the corridor and fight your way outside until you make it to the circular area in the middle. More enemies will appear there so clear them out first before moving forward.
Right below the entrance leading to the pylon lies a download terminal. Continue inside and resupply from the weapon cache to the left. Continue through the locked door to exit.
Once inside, you have to find and destroy the power cores. There are a lot of enemies here so take your time clearing them out before moving in. There are three cores in the ground level that you must destroy; two on each sides while one in the middle, under the ramp. The other ramp leading to the upper platform is located in the middle. As you head there more Promethean Knights will appear. Get rid of them then continue forth.
Make your way to the topmost platform then follow the bridge to the lift. Activate the lift then shut down the beam array. Enter the next two portals afterward.
In the next hallway, resupply using the weapon caches then follow the passage. Drop down to the hole on the ground then continue outside. Covenant drop pods will arrive and the two opposing forces will engage. You can let them exhaust each other's forces or you can join the fray. Fight your way to the narrow passage. Be careful since there will be several drones and an auto-beam turret that will fire in a few seconds once it has you on sight. Once the enemies are cleared go past the turret to reach the next pathway.
Kill the Promethean Knight there and ride one of the Ghosts. Use it to clear the firefight ahead then follow the path until you make it inside the next structure. Head outside to find the second array. Like before, you have to take out the power cores to disable the shields. After destroying all three cores, make your way to the topmost part of the platform and cross the bridge until you reach the next array. Activate the elevator then disable the beam. Enter the portal afterward.
Enter the next portal then engage the covenant forces that will be dropped ahead of you. Activate any of the two door controls then eliminate all hostiles ahead. Enter the large door ahead then resupply using the weapon caches in the next room. Step on the white spot on the floor to be lifted. Exit through the next door.
Fight through a few more enemies until you finally reach the controls. Activate it to trigger a scene.
Once outside, ride one of the Ghosts and boost your way to the next portal. Take note that you must release the boost button every now and then as the Ghost may flip over upon landing.