Particularly the one at the end of the break of dawn quest. I've gone at it 9 or 10 times and I just can't kill the dude! I've tried having a lot of resist cold potions and using the daedric/special weapons I've conjured different things and people to help me but I always end up blasted by either the ice spell or that [censored] electric staff!!
Any ideas of killing him?

Become Etherial Shout, Venison Stew, beating repeatedly with Two Handed Weapon/Shield Bash.
Hit Him with Fire, Burn the Foul Malkoran with a Nasty AOE spell. Use a Scroll to keep His undead Minions at a distance. Circle o Protection and Bane of the Undead are great for keeping a character alive.

I went all sneak mode on him, Dark Brotherhood initiate, and Spectral Assassin, only died twice but on the third try I killed him.