https://exvius.gamepedia.com/Revitalised_Role_Rankings_by_Suede

Short summaries

ReginaRegina: Unquestionably the current strongest finisher, but has even more potential when you can exploit her LB as well; this can be done in a traditional two chainer, one finisher setup by inserting the LB into the chain, or in a more support-heavy team that uses Summer Fina & Lid or Sylvie to grant chain skills to the party. Even with only their LB available to chain with, a pair of Reginas as chainers can also decimate content. All of this comes with the caveat that Regina is incredibly fragile, and her access to strong buffs, mirage and reraise in her kit aren't a complete solution.

Red XIIIRed XIII: While his damage is below the very top chainers, Red XIII makes up for it with strong elemental versatility and good support abilities for a damage dealer. T Stardust Ray is a bit of a clunky chain family for the upcoming few months, but dupe Red XIII or paired with Lila will work fine for now.

AerithAerith: Definitely a unit. Aerith has a lot of great pieces in her kit, but the missing parts can be a serious issue in some fights. In particular: lack of ailment prevention, limited MP sustain in long fights, AoE reraise locked to an expensive LB. These issues can be compensated for or be irrelevant in some fights/setups, and you're left with arguably the best healer. That being said, a lot of her value comes from having a mitigation buff , which can be made largely redundant with Sieghard or the upcoming CG Charlotte, let alone dedicated buffers. In short: uhhh, she's good?

SquallSquall: Similar burst to Cid, but can provide his own imbue and imperil, as well as burst a lot more frequently. Overall, a much less clunky and easier to use finisher than his predecessors. Using Squall as a self-capping chainer is technically a route you can go for, but it doesn't land him among our top chainers currently.

RinoaRinoa: Currently #1 magic finisher, though this is more of a testament to how underwhelming that role is right now. To put it into perspective, her damage output is very similar to Squall's...before imperil. Given that she's locked to non-elemental, that's not great. In exchange for Squall almost doubling her damage, Rinoa does get access to her existing support spells to triple cast in an emergency, and effectively permanent buffs from Angel Wing to keep herself alive.

MedinaMediena: Ms. Curveball herself, going from finisher to top chainer. Damage is well ahead of existing magic chainers and her MP consumption is non-existent, so let's focus on her flaws. She's locked to ice for any serious damage, her AoE damage is considerably worse than her ST damage, and she's mostly dupe only; Christine and Randi come with their own issues as Absolute Zero partners, and all other Freeze chainers suffer from low mods, lack of triple access, or inability to effectively provide support while providing a chain.

RandiRandi: If Regina is the anti-meta damage dealer who requires special consideration to outperform the best, then Randi is the pro-meta damage dealer; versatile with consistently good results that complement current top units, but not exceptional in his own right. Compensating for his poor imperil access, Randi works particularly well with Esther, but can function with T AT users such as Yego, Akstar and Dressy Aileen.

FlammieFlammie: Bit of a muddled buffer. Flammie's next best role is as a decent finisher, but he can't effectively combine both support and damage. As a dedicated support, you have someone who can provide strong stat and elemental resistance buffs, but is otherwise somewhat inflexible and lacking in key functions e.g. HP/MP regen and consistent general mitigation. In light of this, being a gutted Sylvie still leaves you as a potentially powerful unit if elemental resistance is your primary concern.

Dress up EileenDressy Aileen: Powerful T AT chainer with outstanding burst damage and good utility. While nowhere near as problematic as Regina, Dressy Aileen's defenses are underwhelming, and this conflicts with her need to prepare several turns in advance for her burst. If you can compensate for these flaws, she's pretty great overall. Earth/light is an unusual combination of elements, so it's worth mentioning that Yego and Randi work well for earth partners. Additionally, the existence of Excalibur (FFBE) expands Dressy Aileen's non-dupe options further if you can scrounge up an imperil.

Kimono AyakaKimono Ayaka: A SPR-based W AT chainer with some good support moves and two elements to choose from? Groundbreaking. Not really an off-brand Summer Folka & Citra in practice, as Kimono Ayaka puts out the highest damage of all other SPR-based chainers so far by a wide margin. The tradeoff? Lack of imperils, and if you have the nerve to pair her with an AT chainer who can provide them to offset this, you'll be missing out on her big LB chain damage. She also has a couple of deadish turns in her rotation while her unlocks and cooldowns are both down, which mostly serve to annoy me. Niggles aside, a strong unit.

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Let me know what you think.