Romancing SaGa 2: Revenge of the Seven Wagnas Boss Fight (Evolved Form, Classic Difficulty)

Hardest boss in the game so far. You NEED Water Magic (Hasten Time needs to be unlocked by this point), some form of AoE wave clear (preferably Diamond Dust or a water fusion spell) AND Flame Wall (the Earth and Fire fusion spell) for this fight I cannot stress that enough.
My party was: Imperial Guard Male (Emperor), Crusader Male, Crusader Female, Levante Guard, and Nereid.
For anyone looking for some battle tips, he has 3 phases in this fight:
1st Phase (Baby Phase): He doesn't really do much so just go all out.
2nd Phase: He'll start using Firestorm whenever you see the exclamation point next to his portrait in the battle turn bar. You have to get Flame Wall up before he does this or it's joever.
3rd Phase: He'll start spamming Psycho Shot in his spell rotation and honestly the only thing you can do here is pray because at least for me, it was one-shotting anyone who didn't block it.
Anyway, that's just my experience so good luck.
P.S. I think the volume is low again in this video but I didn't think I'd beat Wagnas here so I forgot to turn it up, oops.