This Chapter is so huge that there are two parts to it, each with its own separate bosses and missions. The two parts of the Chapter are treated like separate Chapters, so at the end of the Part 1/2 boss, you'll get a end of Chapter screen like in any other Chapter.
Sub-Boss: DeepGround Commander
Individually, this boss and its minions aren't that difficult. The hard part is beating all of them at the same time with fire coming in at you from all different directions. Start by taking out the regular DeepGround guards and keep moving so that the rocket machines can't get you. After all the soldiers are dead, concentrate on the rocket machines, make sure you keep moving so that you don't get blown away by a rocket. Focus on annihilating the Commander after killing the rocket machines, he will continuously scream 'Hail Weiss' and then will summon three heavily armoured swordsmen. Destroy the swordsmen (make sure you keep out of reach; their swords really pack a punch), keep shooting at him - he has a load of HP, but he isn't that difficult. Once he's defeated, get the Card Key he leaves behind for you and there's a couple of thousand gil that's behind a train to the east.
Like the Pegasus Riders, these guys share a collective life bar. Individually they're easy to kill, a few shots with your rifle or with magic and they're dead. However, the annoying thing about them is that they're flying around with their little jetpack things and trains and other things get in the way, it's very easy to lose sight of them. Just keep running around and keep your eyes peeled for them, don't hesitate to shoot them if they come through your crosshair. It is very tempting to hide behind one of those trains to keep you covered, but it really hampers your attempts to shoot them down.
Escort the WRO squad to the central complex!
- There are 5 WRO squad members.
- Rescue them and escort them all to the central complex without them all dying on you to complete the mission successfully.
Save the surviving WRO members!
- There are 9 survivors.
- Defeat all the enemies around them before they kill the survivors to complete the mission successfully.
Defeat the Deepground commander!
- This mission is obligatory - you have to do it to progress through the Chapter.
Boss: Bloodburst Rosso
Rosso is not only incredibly fast, she's also horrifically strong. Keep running and dodging to get away from her bullets, and jump to get away from her high-damage charge attack. Keep shooting at her all the while, make sure she never gets out of your sights as that usually means that any minute now she's going to run at you and get you. There's a huge amount of items around here, so run around and get them if you seriously need them. After her health is down to about 20% of its total capacity you'll get a short cutscene and now it really begins to get tough. She has a new attack which has two shiny discs that come and cut you from both sides. If you keep near one of the posts you can possibly dodge this. A good tactic for getting Rosso here is to use a Limit Breaker, and if you can throw a fireball at her while she's in the one place you can pin her against a wall and just continue throwing fireballs at her until she either dies or you run out of time. Rinse and repeat this technique for a less damaging success.
Avoid the aerial mines!
- There are a total of 3 aerial mines.
- They're in a passage which you have to pass through, near where you get the mission.
Destroy the robotic assault units!
- There's a straight passage where a robotic assault unit comes out and kills itself by smashing itself against the wall.
- Destroy the robot before it kills itself to complete this mission.
- There's another one in another part of the level, shoot it with blizzard magic to kill it.
Assist the WRO members!
- There are a bunch of WRO members who are trying to unlock a door. They're behind a door that's most of the way down, so you have to equip your sniper scope and a rifle or Cerberus to help them.
- The WRO member will concentrate on unlocking the locks, while you have to guard him. Guard him by keeping your sights trained nearby him. When a Deepground grunt runs out to get him, kill the grunt.
- Protect them until all 40 locks are unlocked.
- If the first WRO member dies, the second will run out to unlock the door and so on.
Defeat the sentry robots!
- There are 10 robots in total.