Yu-Gi-Oh! Episode 85: Hidden Power: Mystery of the God Cards
Episode 85 of 224 of Yu-Gi-Oh!, aired December 4, 2001, 25 minutes. Available with English subtitles and dub where released.
Episode summary
The origin of the Egyptian God Cards is finally revealed. The mysterious Shadi takes Yugi on a journey back in time to the creation of Duel Monsters... and the dangerous powers it released.