I've done it before, but don't ask me how. I got a merc and lvled us both up to 22 because I figured it was going to be hard. It's pure so not great gear, but pretty decent for a pure char. As soon as I get inn, I got maybe 5 sec before he kills my merc, unless he goes for me first that is. After dying 4-5 times with my merc dying more than I could count and not even getting him to half hp, because I had to portal out constantly I gave up for the time being. I'm a bit gimped on the skill tree as I'm going for meteor/frozen orb, but I got 2 + fireball on my staff, 35% cold resistant and half freeze time, still I'm not even close. Should I just lvl until I get 24 and get meteor( 1 1/2 lvl away). Should I get another merc? (I got combat one). I don't see Duriel going down with the current setup. He has always been the hardest boss for me, no matter wich char I play, and normal always seems hardest because of lack of skills.