Six Months Later
You'll be teamed up with Kowalski for this mission. Be wary of the plant life in the jungles as most will actively try and attack you. Others such as the spores Kowalski shoots will explode on impact. Sneak through the shadowy caves of the levels to avoid detection from the Helghast patrols. Your gun can instantly kill enemies with a lone headshot, but the target will have to be perfect dead center. If you mess up and an enemy survives they will call for reinforcements and a normal battle will start.
In most cases, try and kill close by enemies and use the exploding planet life to easily kill groups of foes. If you really get tired of the stealth bit, one of the enemies killed will drop a flame thrower. This deadly weapon will continue to burn Helghast even after the first shot, leaving them crispy critters after only a bit of ammo use. You'll soon be without the caves to protect you from enemy sights and will instead need to duck and move through the bushes. You'll soon come to a Helghast encampment and several of their Exoskeletons.
Restock on ammo and pick up a machinegun. Your initial starting area provides little cover, so swing around to the right and into the small curved passageway. Take down the nearby foot soldiers before aiming for the Exoskeleton bosses. They tend to fire grenades in several bursts, so move in and out of cover to avoid being blown up. When it seems clear, hit the Exo suits hard with machineguns or rockets.
Afterwards, you'll need to high tail it back to the ISA base. You'll be backtracking through the Kaznan. This time the enemies are aware of your location, so there is no need to be sneaky. Still, your main weapon's instant kill headshots are the best means of dealing with the advancing guards. If you really need an extra punch, there is a rocket launcher near the sequences start and several enemies will drop flame throwers.
For the last section of the level you will need to hold the ISA camp. Your priority is to take down the Exosuits, missilers and snipers. The enemy will pound the buildings and turrets, making them unreliable cover. Helghast will continue to spawn from either side, making it unwise to focus on those areas. Narville is your main target to protect, as he is one of the few revivers who cannot permanently die during this battle. If you really find yourself in a jam, hid in the hole on the left side of the map and only take on the few enemies that approach. After a few minutes of getting battered, the mission will end with a scene.