He killed two terentatek single-handily (terentatek are Force-Resistant, and it takes a squad of Jedi to kill one on netural grounds). These terentatek were even specifically more powerful than most - if not all - previously known ones. Pretty much directly after that he defeated the combined force of Uthar Wynn (one of the most powerful Sith in the galaxy) and Yuthura Ban (one of the most powerful Sith on Korriban.) After that he had to fight through an "army" of Sith Masters and Apprentices at the Sith Academy, wiping it out so cleanly that it wasn't until Kaan was it fully recovered again.