Alright, so, Lunatea's Veil isn't a very hard game, but things are always a little harder the first time playing, at least. Maybe you're a master at it now but you weren't always (maybe you're still not, like me!)
So, when you first played, what bosses did you have the most trouble with? I'm not going to rule out the King of Sorrow as an option btw, but I think he's an obvious answer and I'm looking more for the other bosses!
For me I always had, and sometimes still do have, a little trouble with Polonte. I don't even know why? I love the boss and it's really fun but I just always make embarrassing mistakes during it.
Runner up would be Biskarsh, I was terrible at him when I was younger. I'm still not great, even.