Morokei........had to resort to the "blast with firebolt and run away and hide technique". It took a while. Plus the first fight with Alduin..........he got what he deserved second time around though.
My Level 33 1H melee sneak thief found Molokei really easy. I just stood in his face and when the forcefield died smashed him with my sword until he was dead. He didn't defend himself at all.
My toughest was another Nord ruin with TWO Death Overlords in my face as soon as I opened the iron door. If I waited to prepare myself, they opened the door and came after me anyway, using disarm shouts of course. I realise after my character had her ass handed to her about six times that we ought to get the heck out of there. I have not been back. I need to get acquainted with some destruction spells. You have that cool down after shouting, so shouting was useless. Working now on improved Magicka and use of Firebolt spells before I dare to go back. I think I will shout a disarm in turn at them and whack 'em with firebolt.