I was playing my pure mage High Elf play-through today, and attempted "The Staff of Magnus" quest. I went in to the Labyrinthian at level 9 focusing mainly on Conjuration and Destruction magic. Needless to say I got my ass handed to me, but I did however manage to limb my way through to the fight with Morokei. By this time I had leveled to 14 after many intense and lengthy battles with Drauger Deathlords, Wispmother etc. But Morokei, he's one tough son o' [censored] to kill with his terrible lightning bolt and its ability to one shot me. After my umpteenth defeat I reloaded my save and booked it for the nearest exit out of there. After such an embarrassing loss I had to load up my level 55 Nord just to prove to myself that I could indeed still kill something.

So story time being over now, my question is this: What level would you recommend I be at and, spells I have before I return to Morokei seeking to reclaim my honour? ( and melt that Dragon Mask off his face )

The Official Guide lists a suggested level of 24...

Well then, it seems I have a bit of leveling to do. To the nearest dungeon I go.
Thanks.

I did it at around level 18-20 or so just a few days ago, and i think the difficulty was quite appropriate then. I did have to stretch it a bit to beat morokei and also for the first battle with a bonedragon and a bunch of undead. Both those battles i reloaded a few times and used plenty potions, but after i beefed my shock resistance up (i had a +40 necklace in my inventory and used a +18 potion) morokei didnt do that much damage to me and i could stunlock him with impact making the battle if not easy at least quite manageable.

As long as you have the impact perk (staggering) i think you can do it on pretty much any level tbh, though it ofc gets easier with more levels.