Board Thread:Off Topic/@comment-90.149.148.209-20130721230025/@comment-1470368-20140701010443

Fighting Karstaag on Legendary Difficulty is the only right way to face him.

Even then, Karstaag in Dragonborn is nowhere near as hard as he is in TESIII: Morrowind's Bloodmoon expansion. Not even when the difficulty isn't cranked up all the way.