Stargate: Every System Lord Ranked Worst To Best

Sokar was a Goa'uld System Lord who studied the religions of Earth and based himself on the various depictions of the rulers of the underworld, including the Judaeo-Christian Satan. That should be the first thing that people remember about this bloke.

He was once defeated by an alliance of System Lords - including Ra, Apophis and Cronus - though he was able to survive, regaining strength on the planet Delmak, while transforming the moon of Netu into a fire-ravaged hellscape.

He amassed a fleet so grand that he was in a position to attack and destroy many of the other System Lords. The Tok'ra sent Jacob Carter/Selmak to infiltrate his forces, though they were captured. A rescue mission, consisting of SG-1 and Martouf, were sent to rescue him, though they themselves were captured and tortured.

Sokar's forces were far greater than the Tok'ra had feared and they devised a plan to explode the moon of Netu, which would destroy his forces. The plan partially worked, in a sense.

Apophis, under the guise of Na'onak, snuck aboard Sokar's vessel, though was discovered. This distraction bought SG-1 time to escape Netu before the explosion, which did indeed kill Sokar. However, Apophis escaped to Delmak, after which he absorbed Sokar's forces, returning to almost full-strength again.