I haven't really had a "difficult" fight yet. I've had frustrating ones (ice spells seem to do far more damage than they should. There is an ice breath/cone spell many mobs have that will drain half of my health in an instant), but I haven't had any really hard fights. Killing Morokei in Labyrinthian was fairly easy (I had seen the fight when my friend did it, so I knew what to expect difficulty wise) (and so were the other two Dragon Priests I've killed so far). I just summon a Storm Atronach, have him aggro the Dragon Priest, then wail on him with my two bound swords.
My friend, however, died about a dozen times to Morokei. He was about tem levels lower than me when I did the quest (yes, he blasted his way through the Falmer and Dwemer at level 12 or so), so when he got to Morokei he was totally unprepared. in fact, he got one shotted about three times before he started trying to apply any sort of tactics, then after dying a few more times he just went and got the Storm Atronach from the Atronach Forge. However, he beat Morokei due to sheer luck: after siccing Lydia and the Storm dude on Morokei, he hid in a corner (he had also just gotten shot with lightning, so he had almost no health). All of a sudden, Morokei starts dropping hp like a brick. The Storm dude had expired, but his hp was still dropping. He rounds the corner and sees that Morokei is stuck on a rock, and Lydia is wailing on him with a greataxe that also steals health, so she's doing tons of damage. My friend then resummons the storm, then Morokei goes down like a mook. Lydia was also in beast mode for the rest of the game (until she started getting in the way too much), one-shotting almost every enemy she encountered. It was a fairly awesome moment when Morokei died, all thanks to Lydia and messed up AI, then the Thalmor mook get roflstomped by Lydia directly after wards. My friend couldn't even get a spell off before Lydia freaked out and shoved an axe into his face.
