Any dragon priest, death lord/overlord etc..

I had a HUD, but I don't see why having one would make a difference. (obviously I wasn't looking at it while I was fighting)

One or two Ancient Dragons.

First time I fought one, I thought they'd be a push over like all the other dragons.

The HUD has a red dot for the fake versions of himself so that won't help, the way to tell the real one is by the helmet....iirc the real one wears the Ancient Nord helmet and his copies wear the helmet that the Deathlords do.

^^^^^^^ Only I was level 5

You have no idea. I went in there with my level 89 character on Master Difficulty. I died in a minute. I was close to bringing him down to half health once, but then he hit me so hard I flew back into the cave that I came from.

The thing that automatically comes to mind is the very first time someone sent thugs on me. It was a long, exhausting, high risk battle of mobility and attrition.

As for single opponents, i will always remember the first time i met Krosis. It happened quite early and was still undergeared.

A duel on the razor's edge, running from cover to cover, popping out to land a single arrow while desperately trying to avoid incineration.

I have beared his mask ever since

Call me boring, but the longest, most frustrating and time-consuming battle I had was with Alduin on the Throat of the World. Since most of my characters at the time were fire-users who couldn't aim a bow to save their lives, you can see the problem.

Last playthrough, I smartened up. I recruited a shock mage (Onmund) and an ice mage (ilia) as Blades and used a glitch to transport all of them to the Throat of the World when Alduin popped out. It took about 30 seconds to send the frickin' lizard whimpering off to Sovngarde.

I've never understood why people, when playing mages, limit themselves to only one school of magic. Makes no sense.

You did use fire-based magic, right? Seeing as he's the most vulnerable to fire what with him being an ice giant.

Potema - The Wolf Queen Awakened

Malkoran - Meridia's quest

The 3 bosses - final fight of Forbidden Legend

and Karstaag

I don't think I'm skilled enough (level 55) to even take him on without a shout. I have full Daedric Armor and Weapons, 100 in one handed- 70ish in blocking, 50ish for heavy armor :\

My Dunmer Mage character is fire-only because he is both pyromaniac and pyrophobic. So he finds peace while shooting it.

Level doesn't matter, skill does Michael could be level 5 and I could be level 67 and I bet he could still whoop my ass lol

Try being a level 5 and go up against Karstaag. Your hits will but scratch him, and whatever damage you do to him from afar, he'll regenerate back in a second.

I only ever fought him once, on Adept. I would probably get wrecked in a million different ways on Master or Legendary

I find that fight is much, much easier if I bring Spellbreaker.

Low level. Attempting to take out the leader of that set of [censored]s at Uttering Hills Cave.

There was a lot of twisting, screaming and poking following my entrance.

Ooo-err. Sir.