Darkness is the fourth Duel world in Yu-Gi-Oh! World Championship 2008. This world introduces the player to Tag Duels. Neo-Spacian Dark Panther will explain the mechanics of Tag Duel to the player and also puts the player in a practice Duel to demonstrate. After this, he'll become the player's tag partner (this can be changed if the player has beaten any Duel spirit at least 10 times, excluding other tag Duelists and stone tablet monsters. Any Duel ghost the player have downloaded will also work).