I would have to say when I was doing the quest "Lifting the Vale"
I had to go through Serpent's Trail I had to fight 5 ogres and 3 Will-o-the-Wisp's.
It was insane then when I got to Pale Pass I had to fight over 8 of these Undead Akaviri Soldier...
It was the best!

I play a Mage/Thief Imagine this

Just walking around minding your own business in a cave and you see something in the corner of your eye.
You suddenly get hit by my two handed sword with soul trap inchant. (lasts 1min)
Then you get punch in the face by one of my summons.