Karstaag

He can be encountered by placing his skull on the throne at the Castle Karstaag Courtyard to summon him.

He is very powerful and can even give a level 81 character a tough fight. He is resistant to frost spells and is susceptible to fire attacks. He is surrounded by a Frost Cloak during the fight and can ragdoll the Dragonborn away from him.

From Karstaag remains Ectoplasm (×10) and Grand Soul Gems (×5) can be looted.

Tactics

 * Warrior — A warrior with no ranged attack had better be ready for a gruelling fight. Nords as a race will have an advantage. It is highly recommended to bring gear that has Frost Resistance and for your weapon to be enchanted with either Fire or Chaos enchantment.
 * A powerful enchanted bow with the most powerful arrows plus most of the perks in the Archery tree certainly helps. Fall back and directly attack with your bow, keeping your distance. It also significantly helps to have a follower by your side, as a "distraction".

Trivia

 * He is one of the toughest battles in Skyrim according to many players.
 * He can be fought back in Morrowind in his living form.
 * He can knock the player out of the fight causing the battle to reset and his health to go back to full.

Karstaag