Deckard Cain refers to Natalya's Assassin clan as the Khral-Harzhek. However, in the Lord of Destruction expansion pack, the clan from which the assassin class hails from is known as the Viz-Jaq'taar, or Mage Slayers, formed by the Vizjerei to slay rogue sorcerers. It is most likely that the Khral-Harzhek have been retconned into the Viz-Jaq'taar (both are mentioned to hunt down rogue sorcerers), but there is no other information on the Khral-Harzhek.