Chapter III: Rolling Thunder
Grab a Grindlift Notice from the mast on Rig 314 as soon as you're off the line with Command.
[Escort the Assault Derricks to Landown.]
[Kill all incoming Reavers.]
Your rig will come under attack soon, so head on up to the top of Rig 314 and return fire with the turret gun. Make sure to alternate between firing off rounds and cooling your gun, since overheating it will leave you vulnerable to incoming gunfire. For the best results, make sure to lead your shots.
[Defend Dizzy while he repairs the Assault Derrick.]
Some Locust grubs will pop up from the ground while you're defending your position, but just hold out until backup arrives. Make sure you don't miss a chance to grab some Locust weaponry before you get back on Rig 314, since you can run the risk of not having any ammo for your Lancer.
[Climb back on board the Assault Derrick.]
Chapter IV: The Big Push
Swarms of Locust will start streaming out of fissures in the ground, so mow them down with the rig's turret gun. When the Brumak rears its ugly head, use your turret fire to keep it at bay while your rig makes a getaway. Unfortunately, the Locust will hijack the rig to your right, making your rough ride even rougher.
Using the turret won't always give you the best shooting angle, so feel free to get in their faces if you're okay on ammunition.
[Kill the driver of the hijacked Assault Derrick.]
[Protect the Assault Derrick from Brumaks.]
As if the Brumaks weren't bad enough, a Corsper at the end of the road will pop up and ambush you. Fear not, though, since the spider-like monster will turn tail as soon as you see it. Instead, man the turret and take out one last Brumak to continue down the road.
Chapter V: Roadblocks
[Escort the Assault Derrick to the deployment zone.]
In the building to your left, head upstairs to collect a newspaper clipping for your War Journal.
[Eliminate all Tickers so the Assault Derrick can continue.]
Annoying, small, and explosive, the Tickers are everything you don't want to shoot at while you're in tight quarters. Open fire at the doorway until the first wave is dead, and then shoot the rest of them at a distance. If you want to save ammo, try melee them as they rush you, which will knock them flat on their backs.
[Take cover from the incoming Nemacyst mortars.]
You can shoot the Nemacyst at will, but make sure you don't get caught in the crossfire from the tower at the far end of the road up ahead. After the Nemacyst is dead, inspect the inscription below the COG statue at the memorial in the right corner for another addition to your War Journal. Continue up the slope and you'll encounter some more Locust at a burned-out gas station. Blow up the tanks to make the skirmish easier, and then wait for backup to take out the next turret position.
Make sure to check the mini mart behind the station for another War Journal clipping before you head through the next gate.
[Clear the tunnel.]
Don't stray too far from the Assault Derrick's floodlights; the waves of Tickers will pop up faster than you'll be able to pick them off if you Rambo through the tunnel.
If a Ticker is rushing you, use a melee attack to boot it into the air, then shoot away. At the end of the tunnel, you'll have to deal with a Reaver, and this one's itching for a fight. Take cover behind the closest wrecked vehicle and take out the Drone pilots to make things a little bit easier.
Once you're out of the tunnel, you'll have to handle the mortar before the Assault Derrick can go any further.
[Clear the buildings of all Locust activity.]
Once you clear the Locust from the top floor, head straight into the next building when Dom clears a path for you. Take too long, and you'll be on the receiving end of some incoming mortar fire from more Locust grubs. If you see the flash of mortar fire, roll away from cover and hug the walls on either side.
[Defend the Assault Derrick from the Brumak.]
Grab the nearest mortar launcher and hit the Brumak as soon as it exits the tunnel. Make sure to lead your shots or you'll end up hitting your own position. If you want to make sure you don't waste your ammo, wait until the moment the Brumak passes the tunnel's archway.