Anubis arc

After Apophis's defeat in the season 5 premiere ("Enemies"), the half-Ascended Goa'uld System Lord Anubis (David Palffy) becomes the main villain. He possesses much knowledge of the Ancients and their technology. While Earth builds its first interstellar spaceship (the Prometheus) in seasons 6 and 7, Anubis creates an army of almost invincibleKull Warriors and wipes out many of his fellow System Lords. In the season 7 finale ("Lost City"), SG-1 discovers a powerful weapon in an Ancient outpost in Antarctica that annihilates Anubis's entire fleet and also sets the stage for the spin-off series Stargate Atlantis. Ba'al subsumes much of Anubis's power in season 8, while Anubis secretly regains control of his forces. Human-form Replicators begin to conquer the System Lords, but SG-1 finds and adjusts an Ancient weapon to destroy all Replicators throughout the galaxy. Near the end of season 8 ("Threads"), it is revealed that the benevolent Ascended Being Oma Desala (Mel Harris) is responsible for Anubis's original ascension. When she engages Anubis in an eternal stalemated battle on the Ascended plane to prevent his acting on the mortal plane, the Replicators and most System Lords have already been annihilated, and the Jaffa win their freedom from Goa'uld rule.