Selena (Sacred Stones)

Weapon: Tome of Storms

Assist: Positional Assist / Rally Atk/Res+ / No Assist / Flexible

Special: Glimmer / Moonbow / Ruptured Sky

Passive A: Life and Death / Atk/Spd Push / Swift Sparrow / Atk/Spd Solo 

Passive B: Windsweep / Lull Atk/Spd / Lull Spd/Res / Lull Atk/Res / Desperation / Atk/Res Ruse

Passive C: Panic Smoke / Cavalry Buffs / Flexible

Sacred Seal: Swift Sparrow / Atk/Def Solo / Darting Blow / Death Blow 

• Alongside her exclusive Tome of Storms’ powerful boosts, Selena’s extended range and fantastic values in both Attack and Speed all together render her a devastating—and highly consistent—offensive force on the frontline. She will generally benefit more from receiving a +SPD IV due to her dependence on follow-up attacks, but +ATK remains a strong alternative for more upfront damage if unavailable. 
• Her choice of Assist is normally inconsequential unless using her within an Aether Raids Defense team, as one must then take into account the way the AI prioritizes turn order. Keeping Selena’s native Rally may be worthwhile to construct a Rally trap to catch enemies off-guard, but the ubiquity of the Isolation debuff (particularly in Light season due to Mila’s Turnwheel) may make it best to simply not equip an Assist at all to avoid potential mishaps.
• For her A slot, Life and Death 4 comes pre-built into her base kit and certainly makes for a phenomenal choice to further develop her damage potential, in exchange for lowering her defensive stats by five points each and making her more prone to be targeted by Chill debuffs. Should one dislike its potential detriments, other options include Atk/Spd Push (ideal within an  Aether Raids Defense setting), Swift Sparrow, and Atk/Spd Solo.
• Thanks to Tome of Storm’s built-in Null Follow-Up effect, Selena can wield Windsweep to great effect as she can benefit from its counterattack-negating property against physical foes while still being able to perform doubles; this assists greatly in mitigating her poor bulk and makes her quite tricky to deal with. Lull skills are also excellent to break through enemy bonuses, but leave her vulnerable to counterattacks. Desperation is a standard choice for glass cannons and makes for a great budgetary alternative—or if nothing else, Selena’s base Atk/Res Ruse can be kept. 
• Selena’s C slot is flexible. Smoke skills are always solid when paired with refresher support, allowing her to debilitate opposing forces to more easily sweep through opposing forces. Among them, Panic Smoke is especially powerful in a Defense team to reverse enemy buffs. In a cavalry setting, class-exclusive buffs should be considered for greater team synergy.
• For her Sacred Seal, anything that enhances the Fluorspar’s offensive stats will work perfectly, including standouts such as Swift Sparrow, Atk/Def Solo, Darting Blow, and Death Blow.