Secure Perimeter Defenses

After a few moments of chatter, head up the staircase near the arbiter and follow a pair of marines down to a door. Wait for them to open it, then climb the staircase beyond to a door inside the concrete structure. Look for an assault rifle near the door you can grab for additional ammo. Once there, interact with the switch on the left wall to open it.

Neutralize Hostiles in the Hangar!

Once through the door, turn right and follow the path to another door that can be opened via a panel on the right. The hallway beyond contains your first encounter with the enemy, and thankfully you'll acquire a magnum as you pass through the door. Holster the magnum for now, and instead rely on the assault riddle for the many grunts beyond. Use the first container for cover and peek around the side and spray the horde of grunts with hot lead.

A grenade-launching Brute is further up the corridor. Push forward, using the truck and boxes for cover to take down any remaining grunts and jackals, then focus your attention on the Brute. Use the pistol to take him down, taking cover between shots. Or even better: If the Brute deploys a bubble shield, run in and melee him using our aforementioned tactic. After he's down, replace your assault rifle with his Brute Shot.

Easter Egg:

Continue past the door to a dead-end, where you'll witness a humorous conversation between two soldiers, one of whom is begging to be let into a locked room. You may recognize the voices as belonging to two staff members from RedvsBlue.com. Check it out on all four difficulty levels for different conversations.Head inside a doorway on the left into another corridor and immediately seek cover in the alcove on either side, as there are several snipers at the end of the hall. Use the pistol to shoot them while peeking around the corner (if you have trouble, a grenade will work too). Once clear, enter the left room and continue through a door leading to the hangar.

Two doors lead into the hangar - take the left as it's the fastest route to a turret that's vital to your success. Before grabbing hold though, kill any nearby grunts (such as on the nearby stairwell). Now use the turret to open fire on anything that moves in the lower hanger - throughout the battle, three enemy ships will hover near, in preparation of dropping off additional troops. The turret on the ship's front side can quickly take you down, so target it first and destroy it. As soon as the ship drops its payload of enemies, target the Brutes first (you should be able to kill them before they seek cover), then focus on the others. If you begin taking heavy fire, let go of the turret and seek cover behind the wall until your shield recovers.

Get Back to the Ops-Center

Work your way back to the Ops-Center by back-tracking through the same route you took to get here (if you get lost, use the Nav Points to find your way).

As you get close in, you'll encounter a horde of flying drones visible through a gated window. Step a few meters back from the gate and use the assault rifle (if you have it) to safely target the bugs beyond - they simply won't shoot at you as long as you hang back. If you run low on ammo, switch weapons with a nearby teammate.

When clear, enter the lower hallway ahead and climb the staircase to meet up with Sgt. Johnson in the Ops-Center. Follow him up to a door. Before heading through (via the control panel on the right), you may want to consider swapping one of your weapons for a shotgun, via the weapon cache on the left (but retain your Brute Shot and/or Battle Rifle, if you already have one).

Rescue Marines in the Barracks

The door at the base of the ramp leads into a room chock-full of Brutes - this may be your toughest battle yet. The Battle Rifle is key to besting these guys - if you don't already have it, immediately grab one from the weapon cache at the base of the first ramp on the right.

Now use the blast shield near the entrance for cover and zoom in on the Brute's heads to take them down with a few shots each. If you run low on ammo, return to the aforementioned weapon cache for a one time refill (you should have just enough bullets to entirely clear the room). Also, if the Brutes refuse to come out from behind their energy shields, destroy them by shooting the generator at the base.

Eventually, a gravity-hammer bearing Brute will charge at you. The gravity hammer is no toy - it can take you down with a single hit at close range, so it's imperative you take him down ASAP. The battle rifle is more than up to the task, but shoot fast! If things get dicey, toss or launch grenades, and backup into the tunnel behind you, if you must - just keep away from that hammer!

Once the room is cleaned out, grab some additional Battle Rifle ammo from the center walkway above you, then exit through the far door. Turn right inside, shoot the drone that pops out of the hole, then drop on in.

You'll land in a ventilation chamber, where you'll spot several drones darting from one vent to the next. If you just dash toward another hole at the far end, you should make it through unscathed. After meeting with the arbiter, open the lit door.

Evac Via the Landing-Pad

We've divided this long, winding corridor into three section; one for each time it switches direction. Unique to this room is a ventilation duct in the ceiling you can use to ambush the enemy from above. As such, there are numerous methods to get through this room, but here's our suggested process:

Section 1
From the get-go, climb the left-most ladder up to the walkway and follow the left wall up to a ladder leading into the air duct - climb quickly to avoid taking fire.

Now turn around and roam the duct and peer down the ventilation holes to fire at the enemies below - your viewing range is pretty limited, so try circling the holes and duck down to increase your line-of-sight. Also, try firing off a few shots to catch the Brutes' attention. If a group gathers, toss a grenade to take them down.

Section 2
Once you've killed everyone visible from the air duct, drop through one of the holes and continue through the hall. Hang back by the corner and open fire on the Brutes beyond - while there's another air duct above you can make use of, we've found it's difficult to target the enemies in this section from there, so stick to the ground.

Section 3
Use the receded corner preceding the third section for cover. Look for a case of grenades resting on one of the nearby boxes here, so use them liberally. Once you clear out the room, comb the place for additional Battle Rifle ammo, then proceed through the far door and continue through a hallway.

You'll emerge on a walkway overlooking a large cavern. Interact with the switch on the lift to summon it and hop aboard. Wait for your fellow marines to board, then interact with another switch to ride it up a level.

The landing pad has been taken over by jetpacking Brutes! We suggest staying off the pad, and instead seeking cover behind one of the nearby large containers, and using the Battle Rifle to target the pleothra of Brutes. As you reduce their numbers, more will fly in from the sides - they're defenless while airborne, so try to kill them before they land. If you run low on ammo, make a quick trip to the pad and collect any of the weapons from your fallen foes (we suggest the Carbine).

With the landing pad cleared, a Pelican will drop in and collect your remaining teammates. Now make your way back to the Ops-Center to kill the Brutes and rearm the bomb.

Return to the Ops-Center, Arm the Bomb

Follow the Nav point up to a door - get ready to shoot a covenant manning a turret as soon as you open it. Now grab onto the turret and shoot the enemies beyond. Once clear, rip the turret loose and carry it with you through the hall, shooting anything in your path. There are several additional turrets along the way, so replace yours whenever it runs low on ammo.

At the end of the hall, you'll find two snipers on a catwalk in the room beyond, as well as two more turrets on either side of the room. We suggest seeking out a battlerifle from the hall you just reamed, and use it to kill all four of them easily. Now climb up to where the snipers were to grab their Beam Rifle and follow the nav point into the next room.

Use the beam rifle to quickly score headshots on several brutes here - target the one manning the turret in the back of the room first. Duck into the hallway you just emerged from for cover. Once clear, interact with the bomb in the room's center to activate it. Now it's time to escape!

Escape - Find the Elevator in the Hangar

Now it's just a simple matter of following the Nav Point to an elevator in the hanger. You won't face much resistance along the way, except for one hallway with numerous drones, and the hangar itself (use the turret again to clear out the enemies). Then hop aboard the lift and interact with the switch to ride it up a floor.