The monitor teleports the chief back to the control room, and instructs him to insert the index into the control panel. Cortana intervenes, explaining the true purpose of Halo (which destroys the Flood's food supply).
When you gain control of Master Chief, you will need to destroy the Sentinels. You can use some of the glass panels as cover against the Sentinel beam shots.
The Gun Pointed at the Head of the Universe[edit]
The rest of the level mostly serves as a reverse of Assault on the Control Room.
First, exit the control room, and engage the covenant waiting in the corridor. Open the door outside for a second group of covenant. If you get injured, you can ascend the ramp to the middle structure to collect a health pack as well as other weapons (including a sniper rifle).
Head to the bottom of the structure, and hijack a banshee. To do so, you will need to deal with the Wraith on the right, as well as the large number of enemies approaching on ground level. The wraith can be defeated either by sniping the enemy before he enters the wraith, or by continuing to the other side of the building to obtain the rocket launcher. If the banshee on ground level is destroyed by accident, there's a second one available on the bridge.
The waypoint is a platform well above the ground. Fly above it, and kill the elite and two grunts. Land and enter. Cortana explains that your shield system is now modified to disrupt the pulse generator, which you can do by entering the beam. Once you do, move to the back of the room to recover your shields. Fight or evade the sentinels, and return to the banshee.
Breaking Stuff to Look Tough[edit]
Return to the bridge and defeat the reinforcing covenant before proceeding on-foot to the next canyon.
The first half of the installation contains standard covenant forces. Crossing over to the second half shows a fight among covenant and flood. There are two health packs found to the right in the second half.
When you head outside, you will reach the double bridge you seen previously. The first bridge has covenant forces firing on flood on the other side, although the flood is capable of jumping across in a single bound.
The connecting installation on the far side of the bridge contains flood. The corridor between them has one equipped with a rocket launcher, and the second half contains more flood. Exit and cross the bridge once more, shooting down the banshees with the rocket launcher. Eventually, you'll reach a room that leads to a downward elevator. Activating it will release a large swarm of flood infection forms, which poses only limited threat especially when they don't follow you after exiting the elevator. You should now reach the second canyon, where the waypoint marker is visible.
In the second canyon, there is one banshee that tries to strafe you, and it may either be destroyed with a rocket launcher or commandeering a ghost. There is also a rocket launcher and health pack in the section below. Continue towards the waypoint through the tunnel and up the ramp until you reach the tall structure. Approach an duse the banshees on the left; difficulty will arise most likely from the two banshees already in flight, and enemies on the top of the structure (including the ones with the fuel rod gun).
Land at the waypoint, and enter. This pulse generator is defended by Flood. When you are ready, deactivate the second generator and defend against the second wave of flood. There is at least one rocket launcher in the attacking forces.
Exit the generator room when you are ready.
The Tunnels Below[edit]
Enter the Banshee and head to the waypoint that leads through an underground tunnel. This will eventually lead to a locked door. Exit the ghost and flip the switch. The door will only open partially, allowing you to pick off the few flood that trickles through.
Enter the door and cross the bridge to the right. Keep your weapon ready, as there is a large surge when you're about half-way across the bridge. Be sure to take cover on the side of the bridge, especially when one of the opponents has a rocket launcher.
Final Run[edit]
When you exit the underground tunnel, you will see another battle between the flood and covenant. The main threats will be from a flood attack from the right (dispatched early if you throw a grenade into the idling group), a banshee flying overhead, and from the gun turret. There may be a few stragglers if they're destroyed, but pose no threat if you proceed. Once safe, enter one of the ghosts to the left of the turret.
Drive the ghost to the end of the canyon. In the way is a major battle between the covenant and flood which you can drive past. When you reach the ledge, have the ghost jump and use the rock as an improvised ramp.
At the end of the canyon are o banshees along with a major firefight. Park the ghost near the banshees, and board one of them before escaping the combat. If the banshee gets critically damaged, you may have to abandon it and switch to the other one, as the sentinels can easily destroy the vehicle.
With the banshee, land on the platform. You can engage or run past the sentinels as desired, as they will only remain outside.
In the pulse generator room, eliminate all sentinels, then walk into the center to disable it. This will end the current stage, where Cortana explains that she has traced down Keyes, and will use the teleportation system to being you to the Truth and Reconcilation.