Sadow was an ancient sith lord during the Golden Age of the Sith. He had pure Sith blood and he was trained by Lord Simus. Simus was a DLOTS before he was challenged and destroyed by Marka Ragnos, so he kept himself alive with sith magic, and lived as a talking head. After Ragnos died, Sadow and Kressh challenged each other for the title of DLOTS. Sadow eventually got the title through deception. Sadow was also responsible for the fall of the Sith empire, due to his ignorance. Kun was a cocky guy to begin with, but a very powerful jedi even as a padawan. He was seduced by Freedon Nadd to the dark side, and eventually destroyed Nadd when he found the teachings and the Sith Amulet of Naga Sadow. It is widely assumed, and it's very logical, that Kun learned all of his magic from Sadow's notes. The ancient Sith lord were unmatched if you put them with anyone who came after them, so Kun would get owned.