You'll meet up with the rest of the ISA barricade. Two mechs, one ISA and one Helghast, will be fighting amongst each other, so let the heavies take care of themselves. Use your rifle to take down the support shooters standing on top of the buildings. After the Exoskeletons have destroyed one another, move on to the next area. Take cover and use your rifle's iron sights to blast the Helghast.
Rico may get hurt in the cross fire, and revive him right away can expose your position. Try to kill off as many enemies as you can before risking your neck for your buddy. Afterwards you'll be in the gunner's seat of an ISA tank. The driver will lead you where you need to go, so just worry about shooting.
Soldiers will appear on all sides, but can be easily dealt with the tank's machineguns. You'll want to save area of effect rockets for enemies that have armor piercing rockets and tough drop ships.
You'll eventually do battle with several Helghast assault ships and armored tanks. Concentrate on the enemies that are firing on you, as Rico can take care of his own targets. As with before, use rockets as your main form of attack, switching to machineguns only when your main weapon is cooling down.
You'll soon be back on foot and will be separated from Rico and the rest of the squad. The ISA will take the low ground while you provide support from the buildings. There will be a Helghast at a nearby turret that will be blasting your ISA friends. He's oblivious to your presence, so take him down with a brutal melee. Use the turret to help out Rico and the rest of the ISA below.
After the initial fight you'll meet up with several enemy snipers. They are slow at taking headshots at you, so you can easily kill them before they counter attack. Arm yourself with their dropped rifles and pick off the helpless foot soldiers. You'll come to another roof top where you will need to help out Rico and the ISA. You can take out the ground troops that Rico is fighting, but it isn't really needed. Instead, focus on the snipers in the other buildings. There are two in the building across the chasm, one to the right, and two more on the left building.
After a brief scene you'll meet up with Rico and mount up in a few Exoskeletons. The suit's heavy weapons and durability are excellent for tearing down the building ahead. Rico himself will be able to clear out most of the enemies hiding about. When ready, take the road to the left and destroy any heavy craft before finishing off the ground troops.
You'll soon be back on the ground and will only have normal ISA troops helping you. Unlike Rico, these tikes can die permanently, making a long fought battle much more dangerous. The pile of debris in the middle of the ditch is a great place to take cover, but be sure to watch each side for sneaky foes. The Helghast will at first use standard troops, but the next few waves of enemies will include melee troops that can be deadly with their knife slashes. Use your shotgun pistol to deal with close range enemies and prevent them from doing real harm.