Nightmare Valkyries

[SuperPandot]

There isn't much info online about beating the Valkyries on Nightmare. I'm posting my strat below in case anyone else ever wants to see a strategy that worked. There are certainly others, the other topic on this forum mentioned using Schera but she wasn't in my party. 

Since this is NG+, everyone is wearing their best possible equipment. I had 3 Zeram Powders (the more you have the easier it gets), and a bunch of +25 CP food. Accessories and Quartz setup was as follows 

Level 42 Estelle - EP Cut 3, HP 3, Impede 2, Attack 3, Action 3, Cast 3, Proxy Puppet, Lily Necklace

• I had Cast 3 and EP Cut 3, but she never casted anything so consider changing them. Her role is strictly for Morale, passing out items and food for buffs, and using her S-Craft a single time to blow up the caster.

Level 42 Joshua - Impede 3, Attack 3, Defense 3, Action 3, Qilin, HP 3, Gladiator Belt, Grail Locket

• Eats STR food, and then S-Craft over and over. Pray Qilin applies DEF Down and STR down. Impede will hopefully waste the caster's turns as you demolish him. 

Level 41 Kloe - Heal, EP Cut 3, Cast 3, HP 3, Action 3, Defense 3, Proxy Puppet, Lily Necklace

• She pretty much only casts at the start for the DEF buff, otherwise she's the same as Estelle - hand out items and food, S-Craft as a panic button if there are debuffs on her and Estelle or when HP is low.

Level 41 Zin - Defense 3, Action 3, Attack 3, HP 3, Impede 3, Shield Breaker, Gladiator Belt, Grail Locket

• Mainly here to soak hits, but his S-Craft with Shield Breaker and Impede will be valuable for spreading DEF down and it does quite a bit of damage with STR buff from Morale.

 

Bunch everyone up as far back as possible. This can make up to 3/4 of them waste their first turn just moving.

 

Keep in mind there is no reliable strategy for this. It's going to absolutely come down to Crit bonuses and Craft Zero, while simultaneously not having Estelle or Kloe getting randomly Petrified or Insta Killed. Additionally, you need even more luck from having Joshua and Zin apply DEF down from Qilin and Shield Breaker, which only has a 10% chance. 

 

Everyone's first turns went like this to give you an idea.
Joshua - Eat Str + 25% Food
Estelle - Morale
Crit Bonus popped here, so Joshua used his S-Craft.
Kloe and Zin - Both did La Crest to get the party to +50% Def

 

Then it just becomes a battle of survival and praying the big guy doesn't constantly heal everyone. Focus everything on the caster first as it has the lowest HP. I used Estelle's S-Craft, Zin's S-craft, and Joshua's 3 times and that was enough to kill it. Use your Zeram Powder if Joshua is at 0-50 CP. If he's above 50, use food and the gladiator belt will top him off. Use Kloe's S-Craft if everything looks bad. She will die. So will Estelle. That's what the Proxy Puppet is for, they won't lose their CP when they are revived and it cures them of all status effects. 
Once you have a 2nd one down, the fight becomes much more manageable, as you will start to get more even in terms of actions. Keep people up with items and just feed CP food to Joshua/Zin/Estelle as you can, and you'll finish them off.