From left to right: "Forbidden Chalice", "Forbidden Lance", "Forbidden Dress" and "Forbidden Scripture".
All the "Forbidden" cards focus on manipulating monsters' ATK points (or, in the case of "Forbidden Scripture", ignoring changes in ATK and DEF during battles) and card effects, either by granting monsters immunity or by negating their effects.
The woman featured in each card's artwork may represent Pandora of Greek mythology. She later appears as the Effect Monster "Condemned Maiden", implying that she was punished for using the four items, as seen in "Solemn Scolding". The artwork of "Forbidden Scripture" further hints that these items are truly owned by the old man featured in "Solemn Judgment" (identified as God in the Trap's Japanese name). The effect of "Condemned Maiden" makes using Quick-Play Spell Cards like the "Forbidden" series easier, but only once per Duel.
Despite the Greek theme and appearance of each of the cards' artwork, the inspiration behind the series appears to have come from the 4 most notable holy relics of Christianity.
|Forbidden Chalice||Holy Grail|
|Forbidden Dress||Seamless robe of Jesus|
|Forbidden Lance||Holy Lance (Longinus)|
|Forbidden Scripture||Holy Bible|