Summer Freyja

Weapon: Brightmare Horn

Assist: Positional Assist

Special: Glimmer / Noontime / Sol / Moonbow / Luna 

Passive A: Atk/Spd Solo 4

Passive B: Binding Necklace

Passive C: Fatal Smoke / Atk Smoke 

Sacred Seal: Atk/Spd Solo / Spd/Def Solo / Spd/Res Solo

• Summer Freyja's base kit is already quite cohesive and requires little modification outside of:
  • Merely adding another Solo skill in the Sacred Seal to further stack with Freyja's default Atk/Spd Solo 4; doubling up with Atk/Spd Solo 3 is recommended but can be waived for more defensive alternatives like Spd/Res or Spd/Def Solo depending on your intended matchups. 
  • Filling in Freyja's only missing skill slot with an Assist skill; Reposition and Draw Back are fantastic no-thinking-required choices as always.
• With the simple combination of Brighmare Horn, Solo skills in two slots, and Binding Necklace, Freyja can reach an frighteningly high amount of in-combat stats, especially in her Attack and Speed. Combined with Brightmare Horn's built-in forms of Dodge (that is, damage reduction based on how much Speed she achieves over the enemy) and nulling effects that would disable her doubles, many melee foes can find themselves trashed rather quickly if they aren't prepared for Freyja's sheer stat advantage. The only major caveat to consider is Solo positioning, which is easy enough given the extremely large reward from three skills for doing so. 
• Because Freyja is likely to whittle down in multiple fights and some of her performance is reliant on her staying above 25% HP (specifically, the spectrum stats and NFU effects in Brightmare Horn), some form of healing is recommended when using her. You may run Noontime or Sol to self-sufficiently heal up in combat, or specifically utilize outsourced forms of sustain such as dedicated healer units or skills like Sparkling Boost or Heron Wing. 
  • Freyja will usually do enough damage naturally to waive the use of damaging Specials. If you prefer the super offensive approach, however, Freyja's default Glimmer or Defense-cutting alternatives Luna and Moonbow are cheaply at your consideration.

Weapon: Brightmare Horn

Assist: Positional Assist

Special: Noontime / Moonbow / Sol

Passive A: Distant Counter

Passive B: Binding Necklace 

Passive C: Fatal Smoke / Pulse Smoke / Atk Smoke

Sacred Seal: Mystic Boost / Atk/Spd Solo / Spd/Res Solo / Def/Res Solo 

• Freyja can return to her Mythic version's intended roots and perform significantly better thanks to her:
  • Non-Mythic status — she can be conferred any blessing you please and fully benefits from Mythic blessings, rather than providing them and thus never getting them at all.
  • Colorless status, giving her essentially zero type disadvantages outside of the very rare Raven tomes (unlike her Mythic counterpart who has to fight harder against Red threats).
  • Relatively superior stat allocation with Brightmare Horn's Atk/Spd/Def/Res +5 when Freyja is above 25% HP; while Nightmare Horn has Distant Counter built into it, almost no A-slot comes close to providing the convenience and high number of stats that Brightmare Horn already does. Thus, summer Freyja can confidently run Distant Counter in her A-slot with little worry of opportunity costs. 
  • And finally, a partial form of Null Follow-Up also built into Brightmare Horn. While Freyja misses out on the full ability to stop guaranteed follow-up attacks, the "neutralizes effects that prevent unit's follow-up attacks during combat" part of the weapon is usually enough. Specifically, it prevents Impact and Wary-type skills from getting in the way of otherwise confirmed kills requiring Freyja to follow-up.
• If you're already familiar with the original Freyja's playstyle, a lot of aspects should already be familiar to you. Like Nightmare Horn, Brightmare Horn gives Freyja a good and rarely outmatched source of damage reduction, and Binding Necklace ensures a consistent stat advantage over her foes, especially if they dare use visible bonus buffs. 
• The main drawback of Freyja is her maximal performance being tied to her HP being above 25% HP. Naturally, if you're using Freyja in Aether Raids Offense, you'd utilize a form of healing to keep her alive anyway, but this bears highlighting as Mystic Boost and Noontime are prioritized over other skills to counteract this and maximize Freyja's survivability. If you prefer a more offensive approach, have other outsourced forms of healing (like healer allies or Sparkling Boost), or simply believe one of those skills is enough, you may run a damaging Special or another Solo skill in the Special and Sacred Seal slots, respectively. 
• The C slot is open to a Smoke-style skill of your choice. 
  • Freyja's base Fatal Smoke is notably already pretty good as it prevents already-damaged enemies from making a total recovery from their Healing Tower or other healer allies. 
  • Else, Pulse Smoke directly accounts for enemy units reliant on precharged Specials to do significant damage — especially Infantry Pulse teams, Legendary Lilina, and Legendary Sigurd. 
  • Finally, given that Freyja's damage reduction can only account so much for her otherwise just-decent base bulk, Atk Smoke is a pretty easy way to further soften incoming blows from multiple enemies. 

Weapon: Brightmare Horn

Assist: Positional Assist

Special: Galeforce

Passive A: Heavy Blade / Swift Sparrow 3 / Atk/Spd Solo 4 

Passive B: Binding Necklace / Wings of Mercy

Passive C: Fatal Smoke / Atk Smoke / Spd Smoke / Joint Drive Atk

Sacred Seal: Quickened Pulse / Heavy Blade 

• Lacking a Slaying effect or ability to run Flashing Blade or Time's Pulse bites as always for a lot of cavalry Galeforce units, but Freyja can still utilize it effectively with her sheer power and existing tools at her disposal. 
• Galeforce is the namesake of the build, allowing Freyja to make a second action after activating. Whether that second action is drilling further into enemy forces or making a retreat afterwards is your call.
• Heavy Blade should make its way on the build in one way or another to accelerate Freyja's cooldown and account for Galeforce's long cooldown value of 5. The most optimal setup would be running Heavy Blade in the A-slot while running Quickened Pulse in the Sacred Seal; used correctly, this allows Freyja to activate Galeforce on any unit even if they can't counterattack, as long as she doubles and the foe in question doesn't have Guard in some form. 
  • While you can run Heavy Blade in the Sacred Seal instead, this relies rather heavily on the enemy counterattacking as two perfect Heavy Blade hits will only grant 4 cooldown — something that Quickened Pulse directly addresses. 
• Binding Necklace grants a universal stat advantage over Freyja's enemy unit, which can be helpful for Heavy Blade activation. On Eirforce-style team setups, you can alternatively utilize Wings of Mercy to safely teleport into the team regardless of Freyja's original position; it forces adjacency, however, meaning you should be running non-Solo skills (i.e. Swift Sparrow over Atk/Spd Solo) when applicable. 
• Again, Freyja's C slot is mostly complementary rather than essential.
  • Fatal Smoke prevents the opponent from healing should that prove problematic with Healing Tower or sustain skills active.
  • Atk or Spd Smoke softens enemies while easing comparisons for other allies running Heavy Blade or Flashing Blade themselves.
  • Finally, Joint Drive Atk contributes to the Atk comparison condition of Heavy Blade while also providing an Attack swing to nearby allies. It particularly works well with the forced adjacency of Wings of Mercy.