Official YuGiOh tournaments are played using “Advanced Rules” which limits most cards to 3 copies in your main deck, side deck, or extra deck combined. Some cards are considered too powerful, and give players an unfair advantage. Because of these, certain cards are semi-limited (only 2 copies allowed), limited (only 1 copy allowed), and forbidden (0 copies allowed). These list change about every 6 months.
The lists are posted as soon as they are available to us. Typically, a list is release in end of August/beginning of September that goes into effect September 1st, and at the beginning of March that goes into effect March 1st. Occasionally, updates are made during other months, but for the most part, the list gets updated in September and March.
Despite official tournaments using “Advanced Rules“, some local tournaments will play with “Traditional Rules” which does not have a forbidden list. It only has a semi-limited and limited list. By default, any forbidden card in the “Advanced Rules” is a limited card in the “Traditional Rules“.
Other cards, such as the Egyptian God Cards known in Japan as the Three Phantom Gods, are marked as not being able to be used in a Duel. These cards are not allowed in the “Advanced Rules” or “Traditional Rules” tournaments, but some local hobby shops offer unofficial rule tournaments where the cards can be played. The God cards have been re-released in a legal tournament form, however. There are some promo cards that are restricted in certain countries based on the availability of those cards. For example, the promo cards released by Shonen Jump Magazine in the United States are banned in most tournaments outside the United States because they are too hard to find in other countries.
Recently banned cards include: