Chapter 12 of Girls' Frontline picks up in the aftermath of the recent Shattered Connexion Event, and as a result features many new enemies and mechanics from that event.
As with SC, please consult the document here by Sleeper for information about these new threats, or the clear videos attached to each guide for fight-specific in-battle-control.
Unlike Chapter 11, Chapter 12 focuses much more on combat challenges and features fewer map gimmicks or obscure mechanics to confuse and annoy. For players who have cleared Chapter 11 previously, they will need to re-clear Chapter 11-6 to unlock Chapter 12.
To clear Chapter 12, players should have at least two Combat Echelons, one AR/SMG and one RF/HG. For a smoother experience, a third Combat Echelon is recommended, however, and the guides will use three at certain points.
Further, Commanders will need to field multiple HOCs, and the guides expect them to be leveled to at least 60 with appropriate Chips.
Finally: MICA recommended 3-Star Fairies on your Echelons to clear Chapter 12. This is for a reason.
Chapter 12 also brings the latest and greatest in GFL farming maps, 12-4E. We cover an abbreviated list of requirements in the Chapter 12-4E guide, but for a more thorough discussion please consult Ceia's video.
For those who just want the TL;DR:
Base EXP = 600
Core Rates = ~1.2 cores per run average (~1.5 cores per run with rescue SL10 Skill active)
Drag DPS = 416 MOD 2+ >> K11 (SL10) > SOP MOD 2+ > Uzi MOD 2+
Tank = Level 60+ Shotgun (+10 Gold Armor) or M16A1 (With +10 SPEQ farmed from 6-4N) b Formation.
Buff your DPS as required to clear the map efficiently. You can level 1* Fairies here if you give your DPS buffs via HGs/SMGs
Chapter 12 Piano Arrangement
Here is an Piano Arrangement by Schneeheide that was specificly made for Chapter 12!