Belated team assessment. My team was based mostly around "work well with Jessica" and "underpriced characters." Versatility was generally the goal... a whole bunch of nice, small interactions and options, but there wasn't one overriding combo the team was based around setting it up every time. I made this team shortly after a bunch of characters dropped in cost - notably, everyone but Jessica got dropped half a point from their earlier prices. Firefly was just tossed in 'cause, basically. Figured that after a cute theme team (my first team was 4/5 Lunar characters), I'd just go for dungeon power, though I guess you could scrounge up something of a theme based on the 3/5 princess ratio, and an aristocrat & a space elf are sorta close.
Jessica was interesting. I was relying on her damage more than I expected at first, but since her damage is great, that's not really a problem. It's certainly the one area where she's notably better than Rika, who always seemed cheatily good and annoyingly awesome to throw into any team. Jessica does require a bit more careful use than Rika to make the most of her... Accelerate not being the busted Evade booster that Saner is means that Jessica's opening move varied a lot. Accelerate for long games, Magic Barrier against status whores, and often damage for blitzes.
Lyn was chosen to combo with Jessica, mostly. Oomph was another edge Jessica had on Rika, and if we assume that Lyn does average damage on a single strike, being able to crank out 1.6 PCHP damage on a single target is pretty awesome. Kinda thought I'd be using that more, but often it was faster to just have Jessica kill things directly. On Floor 6 and beyond, Purim has Moon Energy for making Lyn into a ridiculous constant-critical machine, and when Jessica was busy, Rena always had Growth as backup buff. (And for those who take all FE characters as average init., this would then allow Lyn to use Moon-Energy powered crits on her first turn... a cute bonus.) Anyway, teams need to have SOME source of physical beatdown lest they get owned by the likes of Marle, and Lyn / Jessica did the job pretty well. She proved a pretty cool holder of Firefly as well.
Garnet was my mage. An early reviver and MT healer who isn't actually THAT frail? Sign me up, especially when she starts getting a good magical beatdown later, too. Garnet's speed was pretty handy, as well. The two-turn buffs get mocked in the DL normal, but in the Dungeon, two turns is an eternity. And with all the backup healing, it wouldn't even be a problem for Garnet to spend half her teams recasting cheap buffs if it came to it. It was also pretty nice that Protect / Shell were nicely different from Purim's Defender and Rena's Protection / Anti. The others were stat buffers - Defender gets owned by attacks that ignore target defense, for example - while Protect / Shell just halved everything. But more importantly, that means they probably stack, subject to interpretation.
Purim was mostly there to do broken things. She's really psychotically good and probably a 3.5 pick to me. Average speed is really the only problem, and Accelerate might (?) help with that anyway depending on interpretations. So yeah, she screws over the many status-vulnerable PCs, has cheap healing, elemental sabers, decent damage, the ability to charge up a super-attack in event of stallers... good times. And that's ignoring her famed defensive buffing.
Rena... well, she's an undercosted heal battery (.5 points?). Who also has some cheaty elemental resists, blocks ID, and has some okay buffs. Rena certainly did help for making sure that for long slogs I wasn't likely to run out of juice - most notable on Floor 6, probably, where having a lot of backup healers makes sure that the burden is evenly spread.
Pretty happy with the team, really. It's too bad I didn't get to see how it would have done on the very late Dungeon floors - Jessica is actually quite good here, since Floor 7's Magic Burst is basically "skip target ridiculously crazy fight." The later floors tend to toss out more full heals, and plus, since Jessica regens MP, it's possible to do things like "status out the last enemy, let Jessica regen back to full MP." I can't really have any complaints because, well, I personally had a sincere vote for my team on Floor 6 which I still think was for the most part easy.
When I was working out a lot of the fights, I was often impressed at how some battles which looked scary at first glance turned out to be pushovers. "Oh, wait, so this character has this one ability that mocks their offense" or "wait, their durability is too bad, they get wiped out before they even go." So the team was definitely better when I expected. Since Neph isn't likely to have too many above-average speed MT OHKOs (the only one I saw was Floor 6 if a team let Zera live - Ba-Boom! + Demon Horde Slash), spamming MT defensive buffs and healing is just a fantastic strategy for many, many, many Dungeon fights. I had figured Floors 3-4 would be the toughest... Garnet would be the only reviver (possibly Floor 5 as well, since Rena's Raise Dead there is borderline), and some of the more broken defensive options wouldn't be available yet (like Lucid Barrier). Firefly helped cover for this pretty well, though, and I'm not sure it was even needed.
An interesting counterfactual is what would have happened without Firefly. Tentatively, I think I'd actually still pass most of the floors. Floors 3-4 would still be exciting... but not too bad? Amusingly enough, this just means that Garnet is the "new" Firefly target, and while she's a suboptimal one, lots of my defensive buffs were MT, and the ST ones could just be piled on Garnet. So I think the team would have hustled it out anyway. The later floors, though, I suspect Firefly would have came into play much more. Floor 6 was where Firefly was really helpful... forcing Royce to waste her Firebird on Lyn rather than Jessica was crucial, and it also obviated any question of needing to kill Rofel since if he did get a turn, all he'd nail would be an extra Lyn sword.