In Anti-Banned Tournaments every card that has either Forbidden, Limited, or Semi-Limited status is treated as Unlimited. Anti-Banned tournaments are mainly popular with duelists who feel that both the Advanced Format and Traditional Format limit cards beyond reason. This is a looser version of a Semi-Anti-Banned Tournament.
Anti-Banned Tournaments occur often but only in in casual play between a small number of duelists or a dueling club where separate sets of rules may be created to fit a small number of different tournaments in order to allow any duelist to join. Anti-Banned Tournaments are only seen in the Metagame; they are never seen in official tournaments.
This is the opposite of a Mega-Banned Tournament where each Limited or Semi-Limited card is treated as Forbidden.