Setsuna

Weapon: Setsuna's Yumi (+Eff) / Spendthrift Bow+ (+Spd)

Assist: Positional Assist

Special: Iceberg / Noontime / Moonbow

Passive A: Atk/Spd Solo / Mirror Stance 3 / Spd/Res Solo, Form, or Bond / Distant Def / Steady Posture / Bonus Doubler

Passive B: Lull Atk/Spd / Null C-Disrupt / Dull Ranged / Null Follow-Up

Passive C: Atk Smoke / Pulse Smoke

Sacred Seal: Spd/Res Solo / Swift Stance / Mirror Stance / Bond equivalents

• A build more specialized against ranged enemies is what one of Setsuna's Yumi's effects is all about: she gets a nice spectrum of stats +4 against bow, dagger, staff, and magical enemies. As a result of the listed skills on this build, Setsuna tends to have more stable matchups and can generally last longer if not indefinitely. Unfortunately, her Defense and Resistance being rather uninspiring at base means Setsuna will have to try harder than other archers at improving her bulk.
  • For a more direct measure at improving Setsuna's bulk, the inheritable Spendthrift Bow does well in this—it directly applies a massive in-combat Atk debuff of -7 against all does (rather than just ranged). To top it off, it even improves Setsuna's damage output with a +7 in-combat Atk boost.
• Fortunately, Setsuna's Speed being at such a high defensive value means Setsuna can afford to consider a variety of non-Spd boosting A slot skills and Sacred Seals. Mirror Stance, for instance, helps out Setsuna's normally low damage output while improving her magic tankability.
  • For those still wishing to invest in Setsuna's Speed—a valuable venture as Setsuna can avoid more doubles and perform follow-up attacks more frequently herself—skills such as Steady Posture, Spd/Res Solo, Atk/Spd Solo, and their Bond, Solo, Stance, or Form counterparts are also on the table. Which one you choose depends on what you can afford which additional stats you'd like to invest in.
  • If you honor Setsuna's Yumi's second condition—that is, having a bonus active and receiving +5 Atk/Spd in return—then Bonus Doubler may be worth consideration. If bonuses in all stats are active on Setsuna, she technically gains better stat boosts than she would with any other A slot skills. However this makes Setsuna dreadfully weak against opponents utilizing Lull or Panic skills as she is absolutely reliant on having visible bonuses at every given time.
• Setsuna's chosen Sacred Seal also reflects the previous point; it's relatively easy to recommend Spd/Res Solo as it benefits Setsuna's bulk significantly for a rather relaxed condition.
• Either Atk or Pulse Smoke enhances Setsuna's ability to persist against incoming mobs of enemies, which is a common scenario in Aether Raids Offense. The former directly debilitates incoming damage, whereas the latter dismantles enemy teams reliant on precharged Specials.
• Finally, Setsuna's B slot is a choice between further enhancing her bulk or increasing her scope of targets. Lull Atk/Spd (or Dull Ranged if you're on a budget—it synergizes with Setsuna's Yumi's specialized ranged effect too) is easily one of the best you can offer the build as it swings Spd-based matchups in Setsuna's favor while shutting down fully-boosted attacks against her. Null C-Disrupt can also be considered if you'd like Setsuna to be your main healer / Firesweep Bow / Windsweep mage killer, though against other foes it's basically an empty B slot skill. Finally, Null Follow-Up significantly improves Setsuna's matchups against units with problematic follow-up manipulation skills, especially Impact skills, Bold Fighter, Quick Riposte, Dark Scripture, Great Flame, and others.

Weapon: Setsuna's Yumi (+Eff)

Assist: Positional Assist / Ardent Sacrifice

Special: Moonbow / Luna

Passive A: Swift Sparrow 3 / Bonus Doubler / Atk/Spd Push 4 / Life and Death / Fury

Passive B: Desperation / Lull Spd/Def

Passive C: Atk/Spd Oath / Rouse Spd/Def/ Joint Hone Spd / Flexible

Sacred Seal: Swift Sparrow / Flashing Blade

• This build is centered around using Setsuna's Yumi offensively. Setsuna's unique weapon provides much-needed additional stats to improve its namesake holder's only passable statline. It has two main effects:
  • First it grants +4 Atk/Spd/Def/Res if Setsuna is fighting ranged enemies.
  • Second, it further boosts Setsuna's Atk/Spd by 5 provided she has a visible stat bonus on herself.
• The weapon's first condition of fighting ranged allies is unfortunately dependent on the enemy's team setup, so much of this build relies on the more consistent circumstance: having a bonus on Setsuna. This can easily be done by running Rallies, Openings, Gaps, and other support skills on Setsuna's allies, but for the sake of build optimization, passive Cs such as Atk/Spd Oath and Rouse Spd/Def and Joint Hone Spd allow Setsuna to self-sufficiently get visible bonuses at her own convenience.
• A focus on attaining bonuses to fulfill Setsuna's Yumi's conditions makes Bonus Doubler a good option to consider. With a self-buffing C slot and other methods of attaining bonuses, the skill can provide an all-round stat increase, though it is extremely vulnerable to enemies running Panic or Lull skills. For insurance against such foes and general reliability, you may instead consider typical Atk/Spd-focused modifiers such as Swift Sparrow, Atk/Spd Push, Fury, or Life and Death; Setsuna only really misses out on defensive bonuses by taking one of these.
• Such a player phase-focused build also makes the Sacred Seals Flashing Blade (faster Special activation) or Swift Sparrow (another consistent source of offensive stats) optimal.
• Finally, the B slot is a choice between Desperation (safety in initiating attacks at lower health while being a cheap general gameplay choice) and Lull Spd/Def (pushes Setsuna's damage even further while swinging Spd comparisons in her favor for more follow-up attacks).

Weapon: Helm Bow+ (+Spd) / Brave Bow+ / Firesweep Bow+ / Fishie Bow (+Spd) / Coral Bow+ (+Spd) / Candlewax Bow+ (+Spd) / Slaying Bow+ (+Spd)

Assist: Positional Assist

Special: Luna / Moonbow / Blazing Wind

Passive A: Swift Sparrow / Life and Death / Atk/Spd Solo / Fury / Atk/Spd Push 4 / Flashing Blade 4

Passive B: Desperation / Lull Spd/Def / Special Spiral

Passive C: Time's Pulse / Spd Smoke / Def Smoke

Sacred Seal: Swift Sparrow / Death Blow / Flashing Blade

• Let's not mince words: Setsuna could have gone with something significantly better than what she got for an exclusive weapon, and nobody will fault you for going with literally any other bow. Aside from your personal choice of bow, however, this build is built largely the same way as other offensive heroes: an Atk/Spd-boosting A-slot (also your choice and preference, though Special Spiral + AOE builds will prefer Life and Death or Fury as well as Candlewax Bow's Fury effect), Desperation or Lull Spd/Def to promote follow-up attacks, and a useful offensive Sacred Seal.
• By fate's whims, the seasonal pirate Brigid came in the same update Setsuna's Yumi did, and her weapon, Helm Bow, is pretty much what the doctor ordered. It provides a stronger built-in form of Lull Spd/Def, which serves to improve Setsuna's follow-up potential and her normally piddling damage while nullifying enemy boosts.
  • However, it is a rather hefty investment coming from a 5 star exclusive seasonal unit, which applies to other very potent weapons such as Fishie Bow (Desperation built-in so you can simply run Lull Spd/Def in the B slot) and Coral Bow (functions similarly to Helm Bow while providing stat support for other allies).
• Fortunately, the generic summoning and Heroic grail pool holds some pretty promising weapon choices.
  • Brave Bow and Firesweep Bow have been longtime friends of Setsuna since launch, and for good reason. The former provides great single-strike blitz damage thanks to hitting twice, though its low Might is not a great match for Setsuna's low Atk these days unless you equip high Atk-boosting A slots and Seals. Firesweep Bow allows for safe initiations by hitting everybody but Null C-Disrupt users for free. However, it tends to lack additional bite compared to other stat-granting weapons.
  • Candlewax Bow and Slaying Bow are ideal for builds running Special Spiral + AOE Specials, as the former improves Setsuna's Atk visibly and thus improves AOE damage, whereas the latter takes away the need to run Flashing Blade in either the A slot or Seal to get the Special ready immediately. Otherwise, however, Candlewax Bow tends to outclassed by the additional stats Setsuna's Yumi offers, and Slaying Bow tends to be a rather boring choice without good Special activation techniques.
• As far as the C slot is concerned, Time's Pulse is the only real premium recommendation as it enables frequent Special activation without Blade skill usage. Otherwise, a Smoke of your choosing or anything else that suits your team will do more than fine!