Nailah

Weapon: Wolf Queen Fang (+Eff)

Assist: Positional Assist

Special: Aether / Luna / Dragon Fang

Passive A: Atk/Spd Solo / Distant Counter / Other Distant Counter or Atk/Spd Skill variations

Passive B: Special Spiral

Passive C: Glare / Atk Smoke

Sacred Seal: Steady Breath / Atk/Spd Solo / Mystic Boost / Fierce Stance

• As Nailah's playstyle leans on activating her Specials when transformed, a Special Spiral build is naturally on the table. After Nailah's Special activates for the first time, Special Spiral will come into play and reduce the amount of cooldown needed — if not fully charge entirely —  to get Nailah's Special ready by two charges. 
• As long as Special Spiral comes into play and considering how Wolf Queen Fang already provides a number of cooldown acceleration techniques (such as CD -1 and neutralizing effects that would slow Nailah's charge down) while dealing a great amount of Special damage, Nailah can choose from quite a few longer-winded Specials. 
• The Special you choose ultimately determines Nailah's build and playstyle.
  • Double Phase Always-Ready Luna (Luna + Spiral): Luna has the shortest cooldown of the options mentioned here at a very convenient 2 CD, meaning that after every Special Spiral charge, Luna will be up and running immediately without requiring any other setup. This allows Nailah to have a nuking option ready at any moment you deem necessary, especially in situations where she may no longer have the strength to bait anymore attacks and is thus forced to initiate attacks in Player phase. 
  • Enemy-Phase Aether (Spiral + Aether + Steady Breath or some outsourced equivalent): With Spiral and some Breath effect active, the normally cumbersome Aether becomes much more manageable to charge, allowing Nailah to make grand use of its huge burst damage and healing in one package. Combined with the increased damage and healing effects from Wolf Queen Fang, Nailah can find herself hitting and healing more strongly than ever, which ideal for survivability-based modes like Aether Raids Offense or certain difficult Hero Battles. 
    • Unless you can outsource Nailah's Breath effect through another ally (like Thórr's Worldbreaker or Brave Lucina's Geirskögul), Steady Breath is pretty much a must as the Sacred Seal option. 
  • Enemy-Phase Dragon Fang (Spiral + Ignis): Similar to Aether, but focuses exclusively on dealing an extremely heavy hit rather than sustain. No Breath effects are necessary to charge Ignis fully because it's slightly shorter-charged at 3 CD, so only one baited enemy attack is necessary after Spiral activation. 
• On any build that doesn't require the additional acceleration from the Steady Breath Sacred Seal, Nailah is free to choose from Mystic Boost, Fierce Stance, or Atk/Spd Solo to improve her tanking and/or damage. Be sure to choose one that fits your phase preferences best. 
• To take Nailah's one-shot damage as far as it can be, a damage-boosting A-slot passive is preferred. Atk/Spd Solo in particular encourages Nailah to abide by her transformation conditions while being active in both Player and Enemy phase. For enemy phase-only builds, Nailah's base Distant Counter allows Nailah to both take on ranged enemies directly. Unless you're using one of its stat-increasing variations, though, it comes at the cost of some stats and thus melee performance. 
• Glare's Gravity-inducing effect isn't terribly necessary on a build designed to nuke and to bait attacks, though it's fine on initiation-able builds. Atk Smoke is, then, a fine alternative to take offensive pressure off of Nailah if she must take multiple enemies in one sitting.

Weapon: Wolf Queen Fang (+Eff)

Assist: Positional Assist

Special: Luna / Moonbow

Passive A: Atk/Spd Solo / Distant Counter / Other Distant Counter or Atk/Spd Skill variations

Passive B: Null Follow-Up / Wrath / Lull Atk/Def / Lull Atk/Spd

Passive C: Time's Pulse / Glare

Sacred Seal: Atk/Spd Solo / Mystic Boost / Steady Breath / Spd/Def Solo / Atk/Def Solo

• Wolf Queen Fang upholds Nailah's combat performance by granting her a variety of stat and Special activation effects. It'd be wasted time to simply repeat all that it does, so we'll cover some accompanying skills that make Nailah a fantastic mixed phase unit for general use.  
• Luna and Moonbow are already good defense-cutting Specials that are strengthened and quickened significantly by the cooldown effects of Wolf Queen Fang. Both have very doable 1 and 2 maximum cooldown, respectively, and their activation can be further shortened if not outright fully charged with the presence of other cooldown-cutting skills like Steady Breath or Time's Pulse (we cover exact combinations later). 
• Null Follow-Up generally provides the greatest B-slot utility as it neutralizes effects that prevent Nailah's follow-up or allow autodoubles on the enemy's behalf. In particular, it's fantastic versus slower enemies with follow-up manipulation — they will be utterly unable to avoid the sheer power of Nailah's incoming Special hit unless they can retaliate with a single killing hit. Lacking that or preferring to increase the power of single Special hits even more, Wrath is a slightly more accessible alternative but requires a little setup as its effects mainly work below 75% HP. 
  • For more favorable matchups and stat comparisons, Nailah may also be interested in the Lull skill line as a honorably-mentionable alternative. Preferably, an Atk-based Lull should be taken to improve on Nailah's survivability. 
• While Nailah's default Glare combos well with the Canto effect of her weapon — which allows her to leave enemy territory safely while surrounding enemies struggle to follow with Gravity active on them — Time's Pulse can prove to be a preferable cooldown-cutting C-passive alternative that can charge Nailah's chosen Special fully or near-full. 
• Finally, Nailah's A-passive and Sacred Seal slots are determined mainly by available outsourced skills and preference between stats or longevity. There's quite a lot you can combo with here, but in short:
  • Distant Counter is generally preferred at higher merges or investment as Nailah would otherwise lack the stats and constitution to take on higher-ring enemies. For lower investment or melee-only performance, you may be interested in Atk/Spd Solo and another Solo choice in the Seal for a hassle-less stat boosts. 
  • Mystic Boost is a generally good survivability option as it provides additional healing alongside the during-combat healing effect of Wolf Queen Fang, and its other effects prove handy if Nailah has no choice but to take stray attacks from Wrathful Staff healers.
  • As specified above, Steady Breath is pretty much a necessity to get Luna locked-and-loaded on any incoming attack in enemy phase. As a note, however, it's not the only way to charge up Luna; you can get it running at the start of every turn with some mix-and-match of Time's Pulse, Wrath, or outsourced support like Ostia's Pulse II. 
• With the above skills discussed, optimal skill combinations are as follows:
  • Generalist / Fallen Edelgard Check (Luna + Null Follow-Up): Transformed Nailah can act as a Fallen Edelgard bait check — and thus take on other tough bulky units with follow-up prevention — by running a simple combination of Luna and Null Follow-Up. With Null Follow-Up and the Null Special manipulation effect from her transformation, Nailah can ensure the kill on Edelgard with a Luna-charged follow-up after hitting past Armored Wall's damage reduction with her first hit. No cooldown acceleration is necessary as it's absolutely vital that Luna hits on Nailah's second attack.
  • Instant-Ready Moonbow (Time's Pulse + Moonbow): the title says it all. At the start of every turn, Time's Pulse fully charges the already shortened Moonbow for a good amount of burst damage in either phase. 
  • Easy Luna (Steady Breath or outsourced equivalent + Luna): an easy, no-commitment way to instantly pop a powerful Luna on foes that dare initiate into Nailah. The Steady Breath seal or some outsourced form of it (like Geirskögul) will easily fill in Luna's 2 CD upon any attack. 
  • Wrathful Luna (Wrath + Time's Pulse + Luna): With a little setup from prior combat, Nailah can have an even stronger Luna fire at any moment for both phases due to the charging from both Wrath and Time's Pulse. When Nailah's starting out, all you have to do is bait out a reasonable enemy attack (like with Steady Breath) as Luna will initially be only at 1 CD. 

Weapon: Wolf Queen Fang (+Eff)

Assist: Positional Assist

Special: Galeforce

Passive A: Swift Sparrow / Flashing Blade / Other Atk/Spd-boosting A-skills

Passive B: Wings of Mercy / Null Follow-Up / Desperation / Lull Spd/Def

Passive C: Glare 

Sacred Seal: Flashing Blade / Blade Session / Swift Sparrow 

• Galeforce has always been a good offensive option on Nailah, but the refinery effects of Wolf Queen Fang — especially its new Null Charge manipulation effect (read: Nailah can't be burdened by Guard effects) as well as remaining Canto and the weapon's many stat swings —  gives it newfound effectiveness tenfold. If you can properly transform Nailah and provide appropriate setup enemy targets, she can excel in her own pretty unique spot as a Galeforce attacker, especially when utilized with other Galeforce chain units on Aether Raids Offense and other modes.
• As usual of a Galeforce unit, there are some standard fixing required to get around its pretty-long Special cooldown. Fortunately, the CD-1 from Wolf Queen Fang already converts Galeforce into a more manageable 4 CD Special. Therefore, Nailah only requires two Flashing Blade-powered initiations to fully charge it. 
  • Ultimately, unless you're employing special support measures (such as using Pulse support like Wolfpup Fang or multiple Infantry Pulses, or running acceleration support like Worldbreaker or Infantry Flash on a nearby ally), you must have some form of Flashing Blade and initiate against slower enemies for this build to perform reasonably well. 
• On your usual Aether Raids Galeforce setup, Wings of Mercy does fantastistically more often than not. It allows Nailah to overcome her otherwise bad initiation movement and teleport next to another setup ally when they fall below half health. 
  • For other applicable modes, Nailah may be more interested in the utilities that Null Follow-Up or Lull Spd/Def offers; the former prevents anti-follow-up skills from getting in Nailah's way, while the latter makes Flashing Blade checks easier while improving her damage meanwhile.
  • Desperation is also a quite decent content-clearing option as it allows Nailah to make two hits consecutively (if she's able to make the follow-up) and avoid the threat of a killing hit when set up correctly. 
• The combination of Wolf Queen Fang's 【Canto (Rem.)】effect, Glare, and Galeforce bears some fascination and a general gameplan: after successfully exiting combat and activating Galeforce, Glare comes into effect and restricts the movement of this combat's surrounding targets. Nailah should then use her additional action to attack another area of enemies and apply Glare yet again, and after leaving that combat, use Canto to safely step out and watch as the Gravity-ridden enemies fail to reach her in such a short distance. 
  • If you can pull this off correctly and eliminate any possible obstacles (especially dancers), this can be an effective escape plan in situations where your team cannot manage to get into an optimal final position. 
  • You can also leverage the Canto effect (whether you successfully triggered Galeforce or not) to purposefully test out nearby traps. In particular, stepping on a Bolt Trap can help if you need other units to use their own Wings of Mercy to step in. 
• We finish off the remaining A-slot or Sacred Seal passive with whichever high-tier Atk/Spd boost you can offer since one of them is most likely occupied by Flashing Blade. Blade Session is typically the best choice as it's unlikely Nailah will be the first to move before a setup unit.