The Legend of Heroes: Trails in the Sky SC: Abyss Worms (Nightmare)

Difficulty: NG Nightmare
Abyss Worm
Level: 80
HP: 15622
STR: 1804
DEF: 1011
ATS: 435
ADF: 411
SPD: 62
Resists: All Ailments
Party: Estelle, Joshua, Agate, Zin
Moveset:
Abyss Worm
Normal attack (has Poison proc)
Lightning Fall: Single-target with Seal proc
Earth-Shaker: All-hitting AOE that is always used if attacked
This fight can be a real pain since there are 8 of them and you definitely cannot survive up to 8 Earth-Shakers in a row if you use AOE attacks. Ironically, AOE attacks are the safest way in defeating them. Boost your SPD with Clock Up EX and cripple their SPD with Clock Down then use Joshua's Evil Eye craft to delay them. The change in SPD on both sides will ensure Joshua will always get his turn before the worms that he hits, allowing you to attack them without them retaliating with Earth-Shaker. The fastest way to kill the worms is with Zin's Thunder God Kick as it has an interesting bug where it hits multiple times based on how many enemies are hit (so 3 enemies will get hit 3 times each), making it very strong against a large group of enemies. Target 3-4 worms at a time and make sure they're Clock Downed and that Evil Eye and Thunder God Kick can hit all the worms being targeted so they'll never get to use Earth-Shaker before they die. Rinse and repeat for the other worms and the fight can be won with little difficulty (Be sure to keep everyone healed since they can poison you).
Sky SC EVO voice mods: steamcommunity...

[@ImBoundChaos]

Abyss worms are the grandmaster

[@Diaryofaninja]

nah, the abyss worms are adios

[@cinfuk324]

how. the worm not use his area skill. hmm..

[@mrbartozio]

They only use their AoE skill if they've been damaged, and Joshua makes sure the damaged worms never get a turn.