Savage Land, Strange Heart (1) - S3-E8
Plot hole: When Kazar discovers that Sauron is really his friend Karl Lykos, Lykos reveals that he was turned into Sauron by Mr. Sinister. However, in the season 2 episode Mojovision when Sauron was attacking Shana, Magneto already knew who Sauron was. Magneto was the master of the Savage Land mutates years before Mr. Sinister was and hadn't been to the Savage Land for many years before then, so if Magneto already knew who Sauron was, then it couldn't have been Mr. Sinister who created him. (00:19:46)