Hi, I am going to tell you how to defeat the 8 Dragon Priests every time I kill one.
Morokei- despite other people saying it was hard, I found defeating Morokei to be fairly easy with a Mage style. All I did was simply kill the two mages holding Morokei with a variety of spells and a Frost Atronach. Then when he was free I just blasted him with Fireballs until he came down. Then my follower (Lydia), clothed simply in a full unupgraded set of Blades armor and sword, started to melee attack him. I then resummoned a Frost Atronach to help her. While Morokei was preoccupied with them, I simply blasted him with Ice Storms, Lightningbolts, Firebolts, Ice Spikes, etc. I mainly used the Ice Storm due to the fact that I was using a Frost Atronach, and they are immune to ice attacks. He was killed easily, and both Lydia and the atronach were both still alive. Not once during the fight did he turn my atronach aganst me. I was level 18 (I believe) when I fought him. Also, It helps to steal the 40% Shock resistent boots next to Arch-Mage Aros Sven's bed in the College of Winterhold, due to the fact that Morokei mainly uses lightning attacks. I don't even believe that I was damaged once during the whole fight. I did not use any healing or potions. Overall, this battle was very easy for me.