This guide comes from https://gamefaqs.gamespot.com/boards/210934-labyrinth-of-refrain-coven-of-dusk/77084873
And is on here for posterity and it's formatted so I can have an easier time reading it than from the Gamefags page.

Perverted Sun dual wielding Theatrical Star build with Furia's Pact. (Make two, for the lulz)
The idea of the build is to stack as much charm and avoid as much dmg as possible, while having passive regeneration, loads of HP, and CRAZY stats... it's literally a build with NO disadvantages, 2 of these are enough to kill anything in the game... heck, with some RNG even 1 of these is.

How to build:
Mad Raptor for Tenacious Speed and Fancy Footwork
Gothic for Dismemberer
Demon Reaper for Heroic Stance and Slippery
Shinobushi for Dual Blade Expert and Tenacious Fingers
Theatrical Star with Anti-Donum Heresy, Tenacious Charm, Healing Chime, Bell Mastery and Cursed Chime.

Equips priority is charm > everything else (there's a point in the game where you can boost 1 female character's stat at random from your group. Make sure that when you take that boost that the only female character in your group at the time of acceptance is a max soul clarity fully built Theatrical Star. Or don't. You do you).

Marginal maze in white rose pact, can even use 2 covens with marginal mazes... make sure all supports are also marginal mazes and at least 1 support *(not attacker)* has Donum Efficiency to reduce spell costs for the whole team.
This has crazy aoe potential; which covers all elements and can heal all brigades. What more can you want?
Stickler/standard is good for these. You might want to take moon stance though, since you can survive 1 hit with Stubborness anyway.

How to build:
Mad Raptor for Swiftness and Tenacious Speed
Demon Reaper for Heroic Stance and Slippery
Gothic for Dismemberer and Reckless Blows
Aster for Stubborness
Marginal Maze for Donum Master, Tenacious Donum, Squishy Body, Lamp Master OR Eclipse

Peer Fortress triple tanking (put them at the rightmost coven for the best effect) with 2 katars on the peer fortresses... essentially they are the spam defend button only type of thing for bosses. Tractie Pact is best for this.
Sun/reliable is the way to go.

How to build:
Mad Raptor for Swiftness and Tenacious Speed
Marginal Maze for Master Masochist and Squishy Body
Aster for Iron Clad Fortune
Gothic for reflexive hardening
Demon Reaper for Repel
Peer fortress for Siege Shield, Guardian's Soul, Tortoise Shell, Unbreakable and Iron Wall.

Aster Knight or any dual wield build, the idea is essentially same, only the weapon changes mostly, I will give example of dual wielding Aster Knight, since the Aster Knight seems to be the best of the dual wielders. Tractie Pact is best for this.
Hotblooded/Standard or moon stance (up to you, moon means that you won't need the Lance Master passive)

How to build:
Shinobushi for Dual Blade Expert, Bypass Armor and Tenacious Fingers
Gothic for Improved Bloodflow, Dismemberer, Reckless Blows
Theatrical Star for Anti-Donum Heresy
Demon Reaper for Heroic Stance
Aster Knight for War Spire, Stubbornness, Lance Master (or Tenacious Strength if choosing Moon) and Armor Piercing.

2x Tractie Pact, 2x White Rose Pact, 1x Furia Pact.
Do you take Eclipse and Lamp Master because you can? Do you say ♥♥♥♥ this guide and do something different? Up to you, but I like being so OP that I cackle at mincing the things that mince me and I hope this guide helps more than just me.

If you can build better please, share the build and make a guide for it.