You can only attack Khan with Energy.
|Name (Tier)||Cost||Notable Drops||Total HP|
|Khan||Free||Amethyst of Summoning|
You can sell the Amethyst of Summoning he drops to The Andaran for 20 Platinum, or sell it in the Market for 250 Million Gold. The second option is advised, there is a lot of good gear in the Book 5 Market that you can buy with gold.