I'm only sorry that I didn't see this note until today. I, too, am having trouble with Jotun and brothers. It seems to me that at least three wizards are needed, although four would be better.
I am a level 41 Ice Wizard and would love to join you and at least one other person to take down those guys.
Make sure you take his brothers out first. I fought him without doing that, and I had to call in a legendary necromancer, grandmaster ice wizard, and a master life wizard to help me out :(