I read in numerous places that the trial isle 5th boss was the hardest in the game. I got him in 40 turns on my second attempt. First attempt I wasn't prepared for him and he wiped me pretty easily but with kabuff and Hendrik doing his cover move the only danger was the time limit. Magic Burst Veronica and a load of Elfin Elixer's from the Casino seemed like it would be a cheap strategy but it seems like a requirement on hard mode.
There is really no point in crafting the strongest weapons since by the time you get the recipes there's only one boss left.
Calasmos was also a little bitch. He wiped me the first time because I didn't put the Sword of Light in my bag to break his barrier like the Teletubby said, but I'm so glad I did because HE SUMMONS THE EVIL LITTLE PURPLE OWLS AND THEY FLOP THEIR TENTACLES AROUND BEFORE THEY HELP HIM ONE SHOT YOU AND IT'S THE BEST. Second fight he never really did much, I didn't even Magic Burst him or use Erik. He also looked way cooler with the mask on.
I did not understand the ending at all, was worried Serenica was going to go back and time and make it so none of the game even happened and everything I'd done for the last 150 hours was pointless. Instead she just wanted to hold hands with Erdwin? Huh. Assuming all those other scenes were from the first game and it was an Easter egg since the credits had all that footage from previous instalments.