Just follow the yellow mark because there is nothing here. When you see second Save Point, take some time to adjust your team and use Crystarium Points. Your default team will be Lightning/Snow/Vanille, but I recommend you change it back to Lightning/Hope/Fang with the follow Paradigms:

• RAV/RAV/COM (default)
• RAV/MED/COM
• MED/SYN/SAB
• COM/MED/SEN
• MED/MED/COM
• COM/RAV/COM

Now spend your Crystarium Points in the following order:

• Lightning: Ravager, Commando, then Medic
• Fang: Commando, Saboteur, then Sentinel
• Hope: Synergist, Ravager, then Medic
• Vanille: Saboteur, Ravager, then Medic
• Sazh: Synergist, Ravager, then Commando
• Snow: Sentinel, Ravager, then Commando

Save your game and go upstairs.

• ENEMY (E-01): Pulsework Knight (x1) (FIRST ENCOUNTER)

After the battle, a new tip pop up telling you that you now have access to all 6 roles. But I suggest you stick with the three primary roles of each character because it is not worth spending your Crystarium Points on secondary roles. They are very costly to level up with little stats gained. Now move forward.

• ENEMY (E-02): Pulsework Knight (x1), Circuitron (x1) (FIRST ENCOUNTER)
• ENEMY (E-03): Pulsework Knight (x2)
• ACCESSORY (T-01): Hero's Amulet (x1)
• ENEMY (E-04): Pulsework Knight (x1), Circuitron (x2)

Left path:

• ENEMY (E-05): Circuitron (x3)
• ITEM (T-02): Bomb Shell (x8)

Backtrack to the main path.

• ENEMY (E-06): Pulsework Knight (x1), Circuitron (x2)
• ENEMY (E-07): Noctilucale (x5) (FIRST ENCOUNTER)
• ENEMY (E-08): Phosphoric Ooze (x3) (FIRST ENCOUNTER), Alchemic Ooze (x1) (FIRST ENCOUNTER)
  *** Special note: Phosphoric Ooze can transform into a new enemy "Alchemic Ooze" if you let 2 Phosphoric Ooze merge together. So I suggest you start with MED/SYN/SAB and wait for Alchemic Ooze to appear, then cast 2 Libra for the datalog.

dead-end:

• ENEMY (E-09): Phosphoric Ooze (x2), Noctilucale (x3), Alchemic Ooze (x1)
• ACCESSORY (T-03): Saint's Amulet (x1)

At the fork, use left path.

• ENEMY (E-10): Noctilucale (x6)
• ENEMY (E-11): Phosphoric Ooze (x3), Noctilucale (x4), Alchemic Ooze (x1)

Turn right.

• ENEMY (E-12): Noctilucale (x10)
• ITEM (T-04): Medicinal Oil (x10)

Backtrack and continue on the main path.

• ENEMY (E-12): Phosphoric Ooze (x4), Alchemic Ooze (x2) (IF SUMMONED)

Turn right at the 4-ways intersection.

• ACCESSORY (T-05): Rainbow Anklet (x1)

Turn around and continue on the main path.

• ENEMY (E-13): Skata'ne (x1) (FIRST ENCOUNTER), Stikini (x1) (FIRST ENCOUNTER)
  (Always kill Stikini first)
   
• ENEMY (E-14): Skata'ne (x1)
• ENEMY (E-15): Skata'ne (x1), Stikini (x1)
• ITEM (T-06): 600 gil
• ENEMY (E-16): Skata'ne (x1), Stikini (x1), Circuitron (x1)

• ENEMY (E-17): Berserker (x1) (FIRST ENCOUNTER), Centaurion Blade (IF SUMMONED) (FIRST ENCOUNTER)
  *** Special note: let Berserker summons Centaurion Blade so that you get full intel and a new enemy catalog.
   
• ENEMY (E-18): Berserker (x1), Centaurion Blade (x1)
• WEAPON (T-07): Rigels (x1)

• ENEMY (E-19): Imp (x3) (FIRST ENCOUNTER), Ahriman (IF SUMMONED) (FIRST ENCOUNTER)
  *** Special note: let Imp summons Ahriman for a new enemy and intel.
   
• ACCESSORY (T-08): Auric Amulet (x1)
   
• ENEMY (E-20): Phosphoric Ooze (x2), Alchemic Ooze (IF MERGED), Imp (x3), Ahriman (IF SUMMONED)
• ENEMY (E-21): Phosphoric Ooze (x4), Alchemic Ooze (IF MERGED)
• ENEMY (E-22): Phosphoric Ooze (x2), Alchemic Ooze (IF MERGED), Imp (x4), Ahriman (IF SUMMONED)
• ENEMY (E-23): Greater Behemoth (x1) (FIRST ENCOUNTER)
• ENEMY (E-24): Phosphoric Ooze (x3), Alchemic Ooze (IF MERGED), Imp (x1), Ahriman (IF SUMMONED)
• WEAPON (T-09): Alicanto (x1)
• ENEMY (E-25): Noctilucale (x10)
• ENEMY (E-26): Noctilucale (x4) (LAST ENCOUNTER), Greater Behemoth (x1)
• ITEM (T-10): Gargantuan Claws (x7)
• ENEMY (E-27): Greater Behemoth (x1)
• ENEMY (E-28): Greater Behemoth (x1), Imp (x3), Ahriman (IF SUMMONED)
• ENEMY (E-29): Imp (x4), Ahriman (IF SUMMONED)
• ACCESSORY (T-11): Metal Armband (x1)

There is another item near the Save Point:

• ITEM (T-12): Ethersol (x1)

Before you proceed, save the game and use all your Crystarium Points on your primary roles. For this battle, I would recommend Lightning/Vanille/Fang since this boss is really weak to debuffs. So, you should remove accessories from Hope and equip them on Vanille.

Paradigm (Lightning/Vanille/Fang):

• RAV/RAV/COM (default)
• RAV/MED/COM
• MED/SAB/SAB
• MED/MED/COM
• COM/RAV/COM
   
• BOSS (B-01): Cid Raines (x1)
  Strategy: I first try brute force alone against this boss and didn't end well. The easily way to kill him is using debuffs.
  • Cast 1 Libra on him. 
  • Start with MED/SAB/SAB and occasionally switch to RAV/MED/COM for healing (or RAV/RAV/COM if you health are full).
  • Until you see Slow, Imperil, Posion, Deprotect, and Deshell on him, do not go full offensive. He may try to remove debuffs sometimes so you should stick to the plan
  • .Once he is staggered switch between RAV/RAV/COM and COM/RAV/COM. Well, he should almost die by the time he is staggered.
  • Once thing to note though, if you see he uses "Seraphic Ray" immediately switch to MED/MED/COM for fast healing.

Make your way to the yellow mark and activate the elevator.

• ENEMY (E-30): Circuitron (x3)
• ENEMY (E-31): Phosphoric Ooze (x2), Alchemic Ooze (IF MERGED), Pulsework Knight (x1)
• ENEMY (E-32): Phosphoric Ooze (x3) (LAST ENCOUNTER), Alchemic Ooze (IF MERGED) (LAST ENCOUNTER), Pulsework Knight (x2)

• ENEMY (E-33): Circuitron (x4)
• ENEMY (E-34): Pulsework Knight (x3)
• ENEMY (E-35): Stikini (x1), Pulsework Knight (x2)
• WEAPON (T-13) Feymark (x1)
   
• ENEMY (E-36): Pulsework Knight (x2) (LAST ENCOUNTER), Imp (x4) (LAST ENCOUNTER), Ahriman (IF SUMMONED) (LAST ENCOUNTER)
• ENEMY (E-37): Greater Behemoth (x1)

• ENEMY (E-38): Circuitron (x4) (LAST ENCOUNTER)
• ENEMY (E-39): Skata'ne (x2), Stikini (x1), Greater Behemoth (x1) (LAST ENCOUNTER)

Take the left door for an item.

• ENEMY (E-40): Berserker (x1), Centaurion (IF SUMMONED)
• ITEM (T-14) Electrode (x3)

Follow the yellow mark.

• ENEMY (E-41): Skata'ne (x2), Stikini (x1)
• ENEMY (E-42): Berserker (x1), Centaurion (IF SUMMONED)

• ENEMY (E-43): Skata'ne (x2)
• ENEMY (E-44): Skata'ne (x2), Stikini (x1)
• ENEMY (E-45): Skata'ne (x1), Stikini (x2) (LAST ENCOUNTER)
• ITEM (T-15): Otherworldly Bone (x2)
• ENEMY (E-46): Berserker (x1), Centaurion (IF SUMMONED)
• ENEMY (E-47): Berserker (x1) (LAST ENCOUNTER), Centaurion (IF SUMMONED) (LAST ENCOUNTER)

Now save your game and prepare for another boss fight.

• EIDOLON (B-02): Bahamut (x1)
  Strategy: 
  • First of all, the game will force you to change your party members and paradigms. But don't worry, the default paradigms is good enough.
  • Start with SEN/MED/MED, then cast 1 Libra.
  • When you health is above yellow, switch to RAV/RAV/COM.
  • After Bahamut attacked you, switch back to SEN/MED/MED for healing then back to RAV/RAV/COM.
  • Repeat RAV/RAV/COM and SEN/MED/MED until the gestalt gauge is filled. You only need 2 paradigms for this fight.