One fun fact about Forbidden Cards is that they are often extremely simple Cards with very few requirements for their powerful effects. Of course, that's usually the reason why they end up being Forbidden. Let's start with the simplest one of them all: Pot of Greed.
Draw 2 cards from your Deck.
Thanks, I guess? Pot of Greed is the definition of gaining advantage out of the blue. There are no costs, there are no requirements, or anything. "Just draw 2 Cards", like a Nike slogan. Just so that it doesn't look so lame, there is one minor rule attached to Pot, which is that you cannot activate it with 1 or less Cards in your Deck. Gaining advantage is so absolute, that you cannot even activate the Card if you aren't going to make up for it!
Pot of Greed has been widely used by several characters in the anime. And no wonder why, as this Card helps them draw into their precious combos that make Duels worth watching. Pot can certainly turn any Duel around, and if you weren't around when this Card, I heavily envy you. Drawing into Pot of Greed was the ultimate salvation a player could ask for, but having it used against you was the ultimate lucksack.
Moving on, we have one of the most devastating removal Cards: Ring of Destruction.
Destroy 1 face-up monster and inflict damage to both players equal to its ATK.
Ring targets 1 face-up monster which must remain face-up until Ring resolves, otherwise Ring resolves without effect. This Card refers to the current ATK of the monster, so you need to take into account every ATK modifier before the monster is destroyed (Equip Cards and the like). The destruction and the damage are considered to be simultaneous, so it does not cause timing issues if you need to respond to monster destruction with a Card like Soul Rope. However, the destruction is a requirement to inflict damage: If you fail to destroy the monster, no damage is inflicted.
Kaiba's favorite combo with Ring of Destruction was Ring of Defense, but sadly, this combo doesn't work with the actual TCG Cards (since Ring of Defense applies to both players instead of one). There are other Cards that can do the dirty job like Barrel Behind the Door, which is even more devastating than Ring of Defense. In real life, Ring was pretty much a game-defining Card. Activating it would usually cause one or both players to lose the Duel thanks to its ability to easily dish out damage in unpleasant doses of over 2000 points. No monster was safe from it. It's no surprise that most rulings that mention Ring of Destruction only use it as a random monster removal Card, due to it's extremely small restrictions.
This fetish for destruction that Kaiba displays will become evident as we move on. Let's take a look at Cyber Jar:
FLIP: Destroy all monsters on the field. Both players then pick up 5 cards from the top of their respective Decks and Special Summon all Level 4 or lower Monster Cards among them on the field in face-up Attack Position or face-down Defense Position. The rest of the cards picked up are added to their respective hands.
At plain sight, we see a very long FLIP Effect. Cyber Jar first destroys all monsters on the Field. Then, both players pick up 5 Cards. Note that picked-up Cards are never considered to be drawn. They are considered to be still within the Deck. Among those, you will Special Summon some monsters, and add the rest of the Cards to the Hand. Destroying the monsters is a separate event, which happens first, while Summoning the monsters and adding Cards to the Hand happens simultaneously, so you can respond with Cards like Torrential Tribute and Drastic Drop Off. All monsters are considered to be Special Summoned simultaneously, but technically, the turn player must decide the position of his/her monsters before the opponent. Any Level 4 or lower monsters that cannot be Special Summoned will be sent to the Graveyard. If Cards cannot be added to the Hand (such as if Thunder King Rai-Oh survived the destruction), these are also sent to the Graveyard.
Cyber Jar packs just too much power. By default, it has Dark Hole's effect, and Dark Hole is currently Forbidden. It also has the power to Summon anywhere from 1 to 5 monsters in the blink of an eye. Cards with less power than that had been dealt with by "The List" as well. Finally, players may end up gaining Cards in Hand for each picked up Card that wasn't an eligible monster, often matching or even beating Pot of Greed. Jar monsters in this game equal big reset buttons. Flipping it in a Duel will always be a lame move due to the instant Field wipe, but it would also bring up a major random factor of not knowing what is going to be Summoned or picked up. It brings bittersweet memories. Kaiba actually faced Cyber Jar while testing his own Deck against his simulator, costing him that the opponent would Summon 4 monsters. This eventually lead to Kaiba Summoning Obelisk the Tormentor and frying all of them.
Tribute 1 DARK monster with 1000 or less ATK. Check all monsters your opponent controls, your opponent's hand, and all cards they draw (until the end of your opponent's 3rd turn after this card's activation), and destroy all monsters with 1500 or more ATK.
Tributing a DARK monster is a cost. When Crush Card resolves, it will start getting rid of monsters. Face-up monsters will have their current ATK checked. Face-down monsters and Cards in the Hand will have their Original ATK checked. Monsters in the Hand and Field are only checked once. The only effect that lasts for 3 turns is checking drawn Cards. This only applies to drawn Cards, so adding them to the Hand doesn't count. The verification and destruction of drawn Cards doesn't use the chain. If you draw a Card, you reveal it, and it is immediately destroyed. If you are within an effect's resolution (such as Dark World Dealings or Allure of Darkness), you reveal the drawn Cards, resolve the effect, then destroy the remaining drawn Cards. So, for example, if you draw into a high ATK DARK monster, and a low ATK DARK monster with Allure of Darkness, you would reveal both. If you Remove from Play the high ATK monster, nothing else happens. If you Remove from Play the low ATK monster, the high ATK monster is destroyed.
Crush Card Virus was much more powerful in the earlier part of the anime series, in which it destroyed every monster in a player's Deck, and due to the rules used there, the player would instantly lose. Kaiba's monster of choice for using this Card was Saggi the Dark Clown. As mentioned before, this Card wasn't Forbidden too long ago, so more players are aware of just how devastating it was. Almost every Deck packed Cards like Sangan or D.D. Crow just to activate this Trap Card and detonate half of the opponent's Hand during turn 1.
But the true definition of devastation comes with the last Card for this article: Chaos Emperor Dragon - Envoy of the End.
This card cannot be Normal Summoned or Set. This card can only be Special Summoned by removing from play 1 LIGHT and 1 DARK monster in your Graveyard. By paying 1000 Life Points, send all cards in both players' hands and on the field to the Graveyard. Inflict 300 points of damage to your opponent's Life Points for each card that is sent to the Graveyard by this effect.
Like we said at the top, Forbidden Cards are usually simple. This Dragon has an Inherent Special Summon, and an Ignition Effect. You can't get any simpler than that. Paying 1000 Life Points is a cost. Sending every Card to the Graveyard and inflicting damage is considered to be simultaneous, but of course, you are required to send Cards to the Graveyard to actually count them while inflicting damage, so Monster Tokens or a Plaguespreader Zombie that has used its effect will not count.
Chaos Emperor Dragon is a sign that says "game over" on a very large stick. Its Summoning requirements were hilarious back on its time, and the years have only made it even easier. It's no wonder that this was one of the first Cards to ever be Forbidden and one of the bunch that has never escaped that status. Many consider it to be THE Card that originated almost every other powerful trump Card that has been designed lately, probably honoring its name as a messenger of doomsday. And this claim isn't too far fetched, as many "big" monsters follow the same template: Inherent Special Summon + devastating Ignition Effect. While it was still legal, the Emperor Dragon was everywhere. If you thought Crush Card was bad, essentially every Deck that contained at least 1 DARK and 1 LIGHT monster could drop this nuke and inflict anywhere from 2000 to around 4000 points of damage. The Duel in which Kaiba used this monster is one of the most epic Duels in the series, and you should definitely watch it if you get the chance.
But when you are Seto Kaiba, a Forbidden Card is a mere tool. If your opponent manages to survive the doombringer dragon, you still have your three Blue-Eyes White Dragons to remind him who you are.
Stay tuned for part 4! If you have any questions, feel free to drop me an e-mail at ness00[at]gmail[dot]com.