Unlike most TCGs (Pokemon, Magic The Gathering), which use a set rotation system to prevent power creep, since 2004 Yu-Gi-Oh! has used ban lists to keep its most powerful cards out of play. In the game's (relatively) early days, Monsters like Chaos Emperor Dragon and Yata-Garasu, as well as powerful Spells Harpie's Feather Duster and Graceful Charity (both of which are still OP to this day), became staples in almost every deck hoping for competitive play, leading to a stifling meta-game that restricted imaginative deck building.
Ban lists are still a point of contention amongst the game's fans, with Konami's quarterly updates being met with a flurry of fanfare and controversy each time they're dropped. Players are loathe to see their favourite cards go, or their tournament-winning combos rendered useless or unreliable.
In a controversial move, Konami chose to gradually take some classic and fan-favourite cards off the ban list, altering their card text significantly to make them suitable for play in the modern metagame. Changing a card's text, usually to weaken their effects, is significantly different from retraining (creating a new card with a different name based on an already existing card). While classic Monsters, Spells and Traps such as Ring Of Destruction are playable again, many fans are unhappy at Konami's decision to alter the legacy of these iconic effects.
For better or for worse, here are the 10 cards that have seen the most dramatic changes, all in the name of tournament play.
10. Crush Card Virus
Once a game-winner, Crush Card Virus -- Seto Kaiba's infamous Trap -- has been altered to such a point it is no longer recognisable as the same card.
Its original text allowed the player, at the cost of one measly DARK Monster with less than 1000 ATK, to destroy all Monsters with 1500 ATK or more in the opponent's hand and field for up to 3 turns after its activation.
Unfortunately, the 2015 version of the card, released in Premium Gold 2, turned it into little more than a run-of-the-mill Trap that takes up more space in the deck than its worth. While the Virus still lets the turn player destroy their opponents' field and hand Monsters with 1500 ATK or more (no doubt useful in such a fast format), the opponent now gets a two-turn shield from any battle or effect damage for free.
Moreover, the three-turn discard has been swapped out, with opponents now able to choose three suitable Monsters to send to the Graveyard from their deck. In a metagame where Monsters are often more useful and accessible in the Graveyard than the deck, giving the opponent essentially three Foolish Burials is a Yu-Gi-Oh! equivalent of shooting oneself in the foot.