Castrum Fluminis is way too difficult

[RyuSaarva]

This fight actually isn't hard at all. The only way you would consider it difficult is if 1) you don't know your job's rotations or 2) you are undergeared. I would suggest upgrading your equipment, learning how to play your job and pay attention to the flow of the fight. It's honestly no different from other boss fights.

actually it is hard for a lot of people, it's a very common rage quit duty and I got it countless times when I was still doing mentor roulettes.

[Mahoukenshi]

actually it is hard for a lot of people, it's a very common rage quit duty and I got it countless times when I was still doing mentor roulettes.

I personally thought Ghimlyt Dark dungeon was quite harder, its last boss constellation to be precise; ignoring that a trial <-> dungeon comparion is iffy, though. Never want to do that one more than necessary and with 50/60/70 roulettes giving only meh xp rewards, I won't have to fortunately XD. I don't have - in comparison - a fair evalutation for Shinryu as the whole party had quite a good chunck more HP than my WAR, thus basically carrying me through the trial. I actually died during the 2nd phase after landing on the ground because I didn't locate the tiny safe spot in time for the huge-ass AOE. Didn't have this impression during Fluminis.