The Black Circle is a secretive cabal of lizard and Dragon-kin assassins under the service of the Great Dragon Kahbyss. The Circle teaches a small repertoire of psionic spells, including some unknown outside the circle. The Circle as a whole has a certain measure of Reputation, although individual Initiates cannot raise this, like an Assassin can.
This is a Prestige Class for Rogues, and they retain the original class's Prime Requisite, in this case, dexterity. As a Psionic class, they possess a Psion's higher degree of success with spells such as deception. Joining the Circle is for life. Initiates cannot become Assassins or Berserkers like Rogues can.