Oggar was one of the wizard Shazam's heroes along with Solomon, Hercules, Atlas, Zeus, Achilles, and Mercury. As one of Shazam's heroes they did great work among mortal man. Shazam taught Oggar both wizardry and magic during his time in ancient Egypt. There was great camaraderie among the heroes - but that wouldn't last. (See my related post here.)
One day Oggar was given a mission by Shazam to go help a tiny nation that was being attacked by a powerful conqueror. Oggar rebelled and refused to go. He accused Shazam of being old, weak, and unfit to lead the seven mighty heroes. Shazam gave Oggar an opportunity to prove his strength, but Oggar failed. For his rebellion, Shazam banished Oggar to wander the world of mortal men, no longer to return to the home of Shazam and the heroes.
Oggar's attempt to rule the world and get his revenge on Shazam is told in the six-part serial "The Cult of the Curse" which began in Captain Marvel Adventures #61 and concludes in #66.
Captain Marvel spends much of his time in this serial trying to defeat Oggar. Billy Batson visited Shazam to tell him of Oggar's arrival and to learn how Captain Marvel can defeat him. Shazam could only tell Billy that Captain Marvel must know that Oggar has one weakness and he must discover what that one weakness is. Armed with that knowledge, Captain Marvel can then defeat Oggar! At the end of the serial, Cap does indeed discover Oggar's one weakness and it does end to Oggar's demise.
Interestingly, Oggar set up his own temple on top of the Rocky Mountains. His temple was complete with his own version of the seven deadly enemies of man. Oggar's version was the seven deadly enemies of Oggar and they included some familiar names - Solomon, Hercules, Atlas, Zeus, Achilles, Mercury, and Captain Marvel!
I really enjoyed reading the "Cult of the Curse" serial. It had lots of plot twists and turns and some parts that just had me laughing out loud. It's a typical whimsical adventure for Captain Marvel. It shines some more light into the wizard Shazam's past and gives us even more reasons to love Captain Marvel - the World's Mightiest Mortal!!