Okay, got my first clear on Madeen after a couple hours of trying. Clear time was just over 40 seconds.
Exdeath (LM1+LM2): R4 Dark Zone, R2 Hastega, MM (USB/SSB2), double dark boost
Kuja(LMR+LM2): R2 Memento Mori, R4 Dark Zone, BLK DMg+30% (BSSB1/OSB), double dark boost
Seifer: R3 Mark of Darkness, R3 Banishing Strike, DMT (CSB)
Raines (LM1+LM2): R3 MementoMori, R4 Dire Heal, Scholar's Boon (BSSB/OSB)
ELarra (LM1+LM2): R3 Allegro, R4 Curada, Gathering Storm (USB)
Rw: Guardian
Magicites: Shadow Dragon (L15 Empower Dark), Hades (L15 Healing Boon),Quetz (2 xL15 Mag Boon), Phoenix (L8 Blade/Spell Ward), Necrophobe (L15 Dampen Holy).
Rough turn order:
Exdeath: Hastega, USB1, Dark Zone spam, refresh Hastega when chain is being refreshed, refresh USB, SSB2, Dark Zone spam
Kuja: MM, Dark Zone x2, BSSB1, Dark Zone spam, BSSB1 when available, Dark Zone spam, CMD1 spam, OSB, CMD1 spam
Seifer: RW, CSB, magicite, Mark of Darkness spam, refresh chain when it runs out, Banish Strike to remove Mighty Guard, Mark of Darkness spam
Raines: MM, Dire Heal x2, BSSB, Dire Heal, CMd1 spam, refresh BSSB, Dire Heal if underHQC, CMD1 spam, OSB
Elarra: Allegro, Curada x2, USB, Allegro, Curada,x2, USB after Phase 2 Terra Impact, Allegro, Curada spam
I first tried with CoD in place of Exdeath, but her BSSB2 is a no go for this fight. The first time I tried it, I died to my own Doom counter with about 35% HP left at 35 seconds. It was encouraging, though, because that was basically a 4-man run since CoD didn't survive the phase 1 turn 3 nuke. I would use her USB, but she can't use white 5 so no Hastega.
I swapped in Exdeath with his USB which provides the same buff as CoD BSSB2, manual Hastega, and went with MM on Kuja/Raines instead. Was also pleasantly surprised to learn that Exdeath has a dualcast dark LM2, so I fully dived him (he wasn't even 4* dived prior) since I had over 900 SPR/WIS motes as well as watered him for HP and MND. I was hoping his Runic would block Stop that was cast on him, but the blasted thing is NAT here. Doesn't matter, though, since he and Elarra still shrugged it off instantly like champs.
Dunno how easy this will be to farm. It took me a couple hours to suss out the rough turn order above. I think as long as I can heal at certain points and have full HP going into Phase 3, it should be stable. Biggest RNG are the goddamn criticals on the opening physicals.
Kuja and Raines continue to be DPS champs even with two year old tech. i got both to cap with their BSSB commands; Kuja was even capping after his en-dark had worn off (my only en-dark for him is his LMR). Good thing too since his R4 Dark Zone ran out. I did water both for magic (and HP), and of.course, gen 2 chain and multiple faithgas, but still, this is great. Raines BSSB was the very first thing I spent gems on to select in FFRk, and it has yet to let me down.
Hopefully this is stable enough to farm. First thing I need is a Madeen with 2 x L20 MAG boon to make this fight a bit easier, then move on from there.