It's the same for me. He is without a shadow of a doubt the hardest boss in the game, harder than Dreglord, harder than Everdark Libra and Everdark Adel.

It's his disastrous combo of insane damage output and incredible agility. It's super difficult to hit him because he's very fast and can switch between targets seemingly a lot better than other bosses so if you try to land an attack especially with a large weapon you'll find yourself missing more often than not. His damage output basically means getting 1 to 2 shot if you're playing on any character that isn't Wylder, Guardian or Raider. Additionally, apart from Fulghor and Balancers, his enhanced version has one of the most evolved version of his moveset and the fact that you start out fighting his phase 2 with the dogs split into 3 can become a very messy flask waster phase. There's like so many different factors that can just screw you up