All the "Forbidden" cards focus on manipulating monsters' ATK (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.
|Chalice||Holy Grail||The selected monster gains 400 ATK||The selected monster's effects are negated|
|Dress||Seamless robe of Jesus||The selected monster cannot be either targeted or destroyed by other card effects||The selected monster loses 600 ATK|
|Lance||Holy Lance||The selected monster is unaffected by the effects of other Spell/Trap Cards||The selected monster loses 800 ATK|
|Scripture||Holy Bible||All other card effects on the field are negated until the end of the Damage Step||Each battling monster uses their original ATK/DEF for damage calculation|