Fallen Corrin (F)

Weapon: Savage Breath (+Eff)

Assist: Positional Assist / Flexible

Special: Glimmer / Noontime / Moonbow / Ignis / Dragon Fang

Passive A: Kestrel Stance / Atk/Spd Finish / Atk/Spd Solo / Atk/Spd Ideal

Passive B: Null Follow-Up / Spd/Res Tempo / Lull Spd/Res / Mystic Boost / Dragon’s Wrath

Passive C: Smoke Skills / Feud Skills / Menace Skills / Flexible

Sacred Seal: Dist. Counter (D) / Null Follow-Up / Breath Skill / Mystic Boost / Atk/Spd Solo

• Fallen Corrin’s strong versatility – a direct result of her colorless typing, infantry skill access, and plethora of stat-enhancing tools — enables good usage of a generalist build geared towards taking on foes during the Enemy Phase, though with the added flexibility of being able to wield her prowess while on the offensive when needed. Either a +ATK or +SPD IV are recommended for improved combat capacity, with the latter coming as an attractive four-point Asset. 
  • Typically, such builds assume access to a Far Save ally as Corrin, in particular, largely relies on her damage reduction effect as a supplement to her stat boosts to actually survive continuous engagements; focusing on melee matchups strictly would thus help her stay largely true to this, as reduction piercing effects are much less common among melee units compared to ranged. 
  • However, the issue lies in Savage Breath’s functioning optimally while she has no allies within two spaces, disallowing Savior strategies if this is desired. The choice to use her as a melee specialist or all-purpose tank then largely depends on personal preference.
• Specials with low cooldowns like Glimmer, Moonbow, and Noontime work well given Corrin’s lack of a Slaying effect, allowing for relatively frequent activations while offering reasonable burst. If utilizing a Breath Sacred Seal, such Specials may be kept for immediate activations on every countattack, or you may want to consider a four-turn option such as Dragon Fang or Ignis for greater damage.
• Regardless of whether you utilize her as a melee specialist or all-purpose tank, however, a standard Atk/Spd boosting A skill should always be taken if you have access to certain fourth-tier versions; she can simply equip the Dist. Counter (D) Sacred Seal instead if you need her to counterattack against ranged opponents. 
  • As for which A skills become worthwhile, she has a few options: Kestrel Stance greatly aids defensive strategies through its persistent Guard effect, Atk/Spd Finish requires a bit of careful space management but provides arguably the best overall bonuses through more damage and healing, and Atk/Spd Solo and Ideal are her best options if pure stats are preferred. 
    • Please note, though, that Unity skills are not recommended for Fallen Corrin. They are excellent skills generally, but Savage Breath neutralizes any stat penalties she has so Unities bear no effect beyond their base +5 stat boosts — not to mention the fact that they require consistent proximity to her team.
• Null Follow-Up is, for all intents and purposes, a non-negotiable aspect of Corrin’s build as it negates effects that are far too prevalent in the current landscape that otherwise inhibit her performance severely. Thankfully, it’s accessible as both a Sacred Seal and through external buffs (such as Inf. Null-Follow), but if she can’t access it through such means — it must be used as her designated B skill. 
  • If she’s able to keep her B slot open, though, there are a plethora of choices she can consider that work well in whatever setting. Spd/Res Tempo is ideal if versatility is preferred as it ensures immunity to Guard, while Lull Spd/Res and Dragon’s Wrath are excellent to push her damage ceiling higher. For all-purpose tanking specifically, she can consider Mystic Boost 4 to aid her weaker ranged matchups.
• Fallen Corrin’s C slot is largely flexible and open to skills like those that directly pad her stats for enhanced performance, including Menaces, Feuds, and Smoke skills — just don’t use Joint Drives unless you are specifically assuming she will keep one ally around her, such as for melee specialist builds. For her Sacred Seal, if she’s not using Dist. Counter (D) or Null Follow-Up, those that enhance Atk and Spd should be prioritized, while Breaths and Mystic Boost remain good alternatives for miscellaneous goodies.

Weapon: Savage Breath (+SPD)

Assist: Positional Assist / Flexible 

Special: Glimmer / Draconic Aura / Bonfire 

Passive A: Atk/Spd Solo / Surge Sparrow / Atk/Spd Ideal

Passive B: Dragon’s Wrath / Null Follow-Up / Special Spiral / Spd/Res Tempo / Seal Res 4

Passive C: Atk/Spd Menace / Time’s Pulse / Tempest Skills / Smoke Skills / Flexible

Sacred Seal: Null Follow-Up / Atk/Spd Solo / Flashing Blade 

• Interestingly, Fallen Corrin shines quite well in the context of offensively-tuned strategies, as maintaining Savage Breath’s requirements becomes much easier given she’ll be engaging enemies away from her allies anyway. This build capitalizes on this — and while this is somewhat “meh” for competitive modes, it’s perfectly workable for general gameplay purposes. A +ATK or +SPD IV is again recommended.
• Any A skill that enhances both Atk and Spd works fine here to frontload as much damage as possible, including her default Atk/Spd Solo. That said, Surge Sparrow may be of particular note to those with the available resources to supplement her damage with considerable healing upon Special triggers, as well as Atk/Spd Ideal for slightly higher values in obtainable stat boosts.
• The Dragon’s Wrath 4 B skill is excellent for its dual-phase functionality and true damage bonus (similar to the one built into her weapon), helping Corrin tack on further upfront firepower; it also modestly increases her potential damage reduction to 47.5% from her foe’s first hit. Alternatively, she can consider Null Follow-Up for heightened consistency against common enemy mechanics (though it can easily be used as her Seal instead), Special Spiral or Spd/Res Tempo for emphasis on Special triggers, and Seal Res 4 for a guaranteed +11 damage against most foes.
• The same overall motif of increasing damage and the power of Corrin’s initiations applies to her choice of C skill, including those that aid her damage directly (e.g. Res Smoke, Atk/Spd Menace) and indirectly (e.g. Time’s Pulse for hastened Special activations). Tempest skills are also interesting to expand her mobility and make it even easier to maintain a distance from her allies, though they're not quite as effective as they would be on someone who could combine them with Galeforce.