Lol wow, I just did this.  You bring a cleft hoof as close to auch as you can (keeping it in the bone valley place) and kill it.  Summon huge worm, hit him a couple times to make him mad, and run into auch, around the corner, to break line of sight.

He apparently can't come into auch, and just sits on the other side of the wall, angry.  In about a minute... he just dies.  Big angry heart attack or something.

Nice find man!  Could not find help for this quest... now I got my dagger lol.


Be careful though, try to get behind the wall asap.  His poison does 2200 damage, and his melee is nothing to laugh at either.  But as long as you can make it to the other side of the wall... you're gold.