Trails in the Sky SC : Abyss Worms (Nightmare)

Sylpharion is useful ?!
Read Description :
Level : ~55 (I killed some shining poms, but you can do this at a lower level. It's just a bit easier this way)
Quartz : Action 2 and Cast 2 on every characters + one wind orbment as they are weak to this element (except for Agate as he usually has better things to do)
Party : Estelle, Agate, Tita, OIivier (Taking Kloe is obviously the best choice here and make this battle way easier)
Strategy :
First thing to do is to pick Agate instead of Schera at the beginning of the game for this fight in particular. Like... Seriously. Playing Schera in Nightmare mode is like playing Nightmare ++. But hey.. You might as well give it a try! Anyway, not to mention that with his AoE, pushback, delay, impede craft, Agate is super strong and can also easily kills the 3 monsters at the start of this fight thanks to his S-Craft. Next, you have to manage to survive and reach one of the four corner of the map. You also can use petrosphere. A bit of luck might be needed, but you'll eventually reach one. Then the Worms will block eachother and only two in the worst case scenario should be able to hit you at close range. The others either do nothing, or use lightning, which deals only 700-800 dmg. Next, AT Delay one with Agate, kill it. Repeat. Using clock down can help a lot. Also, you don't want to hit them all at the same time as they retaliate with Earth Shaker, a big AoE Craft which deals 2000~ to your characters. Anyway... Easy right ?...
Certainly one of the hardest fight in game, not including Kurt in the prologue who's cookie + RNG-dependant, and Loewe at the end of the game because you will only spam Zeram powder/capsule and kill him this way as he's way too overpowered otherwise. (If someone managed to beat him without items, and without being like level 999, congratz, truly. I really want to see how in a video!)
PS : Malwarebytes, come on, don't pop up while I'm recording !

[@leonchen89]

Thank you for the video. This strategy really worked. Running to the corner was the key. ❤❤

[@Hanesboi]

Nice! That's a good strat for an otherwise cumbersome boss just because of that Earth Shaker ability.