Hello, im on the collage of winterhold quest where i need to get the staff of magnus, and im trying to kill the dragon priest morokei but he wont take damage, even after I killed the two mages giving him power, I've tried to kill him by cheatstoo but nothing works, how can I do this?

Reload a previous save (maybe the autosave that leads into that part of the dungeon) and try again. Must be a bug, is the blue shield effect still around him? (From the mages)

The blue shield was still on him yes, but it worked with the "killall" cheat. Though I have another problem right now that has been bugging me, my screen blinks all the time like im in water, hard to explain, i hear the water sound and the screen blinks

Impatience.

Once you have dealt with the 2 mages you ought to be able to distract him with a Conjured Spirit or Atronoch.

It wouldn't hurt to have a companion with you to run interference either as the guy is a beast.

However you ought to be able to lure him out of the main chamber and through the pillared corridoor.

Once there you can have a good old fashioned Western Shootout.

If you're careful and use cover wisely you shall win.

Azrael
The Nord with the Sword

Cough ... archery is your friend.

So you both decided to comment without reading his post at all? Morokei isn't taking damage for him, it's nothing to do with tactics. Also summons are usually useless against dragon priests, they will take them from you, then use them against you.

Then you said he still had the blue aura around him.

What?