Obvious Rule Patch / Magic: The Gathering

There are times Magic: The Gathering has had to give cards errata. It is currently not Wizards of the Coast's policy to reword a card for simply being too powerful — overpowered cards simply get banned — but there are quite a few cards that have different wordings due to rules changes, or interactions that literally break the game (as in, "create situations that the rules don't cover"). This was exacerbated with two major rules changes ('96 and '09).

• While errata is no longer used to Nerf overpowered cards, a few cards have errata to close exploits that hadn't yet existed when they were originally released, such as Mox Diamond and Lotus Vale not allowing you to "cheat" past their requirements.
• Back when they did errata cards for power reasons, Time Vault was errata'd multiple times with various awkward wording to ensure there was no way to easily untap it and gain infinite extra turns. (Ironically, one of the errata did allow it to infinitely untap for free without getting more extra turns, which meant people just used it to kill the opponent on the current turn instead. The next erratum erased this interaction.) The current rules text, while much simpler than even the original card, makes the card obviously broken in half (and banned almost everywhere).
• Animate Dead has generally worked as it was originally intended: it enchants a creature and brings it back from the dead, but the creature dies if the enchantment goes away, just like the various Necromancy spells from Dungeons & Dragons. However, the exact mechanics of this process, if and how a creature that would be immune to Black spells can be targeted by this, etc., have caused Animate Dead to be a nightmare of errata and Magic legalese. There's a reason only two other cards like Animate Dead have ever been made, and most other reanimation spell thereafter were ether instants, sorceries or are permanents that use nontargeting abilities to get the same "If this card leaves, the creature dies" effect without the complexity.
• The Sixth Edition rules changes were done, in part, to deal with all the Obvious Rule Patches that were made to the game over time, such as how Wizards of the Coast dealt with Mana Vault. The card's text states that it taps for 3 colorless mana, doesn't untap unless you pay 4 mana, and deals 1 damage to you each turn it stays tapped. The problem is that the game rules stated that a tapped artifact didn't function, so the abilities that keep it tapped, let you pay 4 to untap it, and make you take 1 damage if you don't untap it shouldn't work. The solution was a patch that allowed Mana Vault to work as written. After Sixth Editon, they simply removed the rule about tapped artifacts not working, since it really only mattered in a few situations anyways.
• The Sixth Edition rules change added, "The Stack," a universal first-in, last-out resolution system in which Instants and activated abilities (that don't say otherwise) can be played in response to other spells and abilities. This mostly works fine, except that a few kinds of interaction are faster-than-instant and can't be responded to:
  • Paying costs (either the top right of the card or everything in front of the colon on an ability) happens immediately and can't be responded to. For example, a player can cast Control Magic (gain control of target creature) on their opponent's creature, but the opponent can sacrifice the creature to a spell or ability and the first player can't do anything to stop it.
  • Targets are chosen when a spell is announced, not on resolution. Any ability triggered by targeting something do so before any player can interact with whatever is triggering them and still happen whether it resolved or not.
  • Mana abilities don't use the stack. This is itself an Obvious Rule Patch to avoid every spell creating an obscene number of stops (in most cases, a spell that costs X would create X+1 stops, one for the spell and one for each land tapped to cast it). The game defines a, "mana ability," as an activated ability that makes mana, doesn't target anything, and has no inherent timing restrictions (like a Planeswalker's loyalty abilities). This has led to some cards winding up with the bizarre text, "activate only as an Instant," when they have other effects besides making mana but still qualify as a mana ability. Lion's Eye Diamond is the most famous of these, which discards the player's hand as a cost of activation. Without this errata, complex interactions are allowed that include casting a spell in hand with the mana generated by the ability that discards the player's hand (further complicated by the card Infernal Tutor giving its controller a bonus for resolving it with an empty hand, which they'll have when all is said and done). The errata forces the player to finish resolving the cost before they can draw on the mana created.
  • For those very rare spells that are faster than instant speed, they use the keyword Split Second, which means that the spell is added to the top of the stack and resolved before anything else happens.
• Before Time Walk was released, it was phrased "Target opponent loses next turn", which itself needed to be rewritten after people started misinterpreting it as "Target opponent loses the game next turn". (It's still massively overpowered though.)
• The standard Constructed Deck construction rules of today are a pretty important rules patch. Originally, there simply were no deck construction rules whatsoever — a "deck" of five Fireball, five Channel, and five Black Lotus would have been perfectly legal and a very reliable first-turn win. Revised Edition added a minimum of 40 cards in a deck. Both of these were intended to be balanced by players not wanting to bother hunting down the requisite number of copies of specific rare cards, but Wizards quickly learned that this just wasn't the case, and by Fourth Edition, the modern rules played by today came about — at least 60 cards, and no more than 4 copies of any non-basic-land card.
• A few powerful creatures (such as Serra Avatar, Darksteel Colossus, Purity, Dread, Guile, Vigor, Hostility, Progenitus, and Kozilek, Butcher of Truth) have an ability that prevents them from going to the graveyard, shuffling them back into the deck instead. While this looks like an advantage, it was done to prevent players from discarding these powerful creature cards on purpose so that they can revive them using way cheaper Animate Dead spells. This is not an idle concern, as entire decks are built around this very tactic. When it was noted that the original version of this ability technically still put the affected cards into the graveyard for a brief moment during which the revival shenanigans were still possible (albeit difficult), later and more powerful cards got a tweaked version that specifically avoided even this brief moment.
• Some creatures have abilities that only trigger "when you cast [the creature]" (which means it must have at least went to the stack as a spell, as opposed to being directly put into play.) to prevent reanimation or flicker shenanigans.
• There are permanents that have abilities that will temporary exile a permanent when it enters the battlefield till it leaves play. Originally the triggered abilities to exile a permanent and to return the permanent were separate abilities. This had the unintended interaction that if the ability's permanent left play before it resolves, it would then trigger the "return from exile" ability on the stack before the permanent is exiled, essentially removing it from play for good. This made flickering very powerful in getting cheap removal. On top of this, this method can also cause one of the few true infinities that lead to draw games: If the only permanents in play are three of these types of cards, it leads to an infinite loop of them exiling and returning each other. Later cards would fix this by combining the two triggers into one ability to avoid this abuse again.
• There are effects that make an additional combat phase followed by another main phase to allow the player to attack again (usually also untapping all attacking creatures as well). These used to be restricted to instant, sorceries or hard to trigger enchantments and even on creatures only for the first time they attacked in a turn. Then players figured out that on the creatures they could use flickering effects to reset the creature, allowing it to trigger its effect again. This got hilariously broken by the time Aurelia, the Warleader came out, and got supported by the overwhelming amount of flickering cards from the Innistard block that allowed her to trigger her effect multiple times in a turn. This made it so that future instances of the ability on creatures and some other permanents wouldn't trigger additional combat phases outside of the first combat phase of a turn without a heavy cost or hard to trigger to prevent abuse.
• Phage the Untouchable has an ability that causes you to lose the game if you didn't cast her from your hand. Like the above examples, this is done to prevent "reanimation" exploits. (It should be noted that Phage's other ability is to cause the opponent to lose the game if she manages to lay a finger on them, so ensuring the "Impractical" part of Awesome, but Impractical was kind of necessary in her case.)
• The introduction of a "Planeswalker" card type almost fifteen years after the game's inception necessitated such a patch. Planeswalkers needed to be valid targets for damage, but since they hadn't existed previously, all existing damage spells only targeted creatures and/or players, of which planeswalkers were neither. So a special patch rule was added that allowed spells to redirect their damage from a player to their planeswalker. The rules tolerated this ugly workaround for nearly a decade before a sweeping errata was made to change every previous instance of "damage target player" to "damage target player or planeswalker" and eventually changing "damage target creature or player" to "damage any target".
• The "M10" major rules overhaul included changes to the combat rules, which would have made the Deathtouch ability almost entirely useless, so, in the M10 rules, Deathtouch got a special rule exempting it from the new combat rules. It has since been further patched to work properly under the new rules.
• Mindslaver lets you control a player's turn, but
  • You cannot make the other player concede the game — nor prevent them from conceding the game if they so desire. Rule 104.3a says concession is a special action that can be taken at any time by a player and is completely unstoppable by anything else.
  • Back when mana burn existed (it was later deleted for being not particularly impactful), there was a special rule that it didn't apply when someone else controls your turn. Otherwise the correct thing to do would be to simply tap all lands and deal a ton of damage to yourself, which is less cool than using your own cards against you and making terrible decisions.
  • The original rules for controlling another player meant that the controller could see anything the player could see. In competitive formats, this includes the player's sideboard, meaning that casting a Mindslaver or Emrakul in game 1 gave that player perfect knowledge of what cards they could expect the opponent to bring in for the other game(s) of the match. This was errata'd out when Emrakul, the Promised End was seeing extensive Standard play.
• When Stoneforge Mystic got banned, the announcement came a mere 10 days after the release of an event deck containing two copies of it. Wizards of the Coast added a stipulation to the ban that that deck was legal even with the two Stoneforge Mystics, provided that it had not been modified in any way.
• The original rules for spell resolution order were such a maze of patches Sixth Edition decided to replace it with an entirely new system.
  • Before Sixth Edition and revising the system into "The Stack", spells and effects used "The Batch" system, similar but complicated by the fact that spells and effects are separately resolved according to their speed. So instant speed spells and effects were stacked with each other, as were Interrupt speed ones and so forth. The theory was that this was to help interrupt speed effects resolve first by pausing the instant batch before anything else was put on it. In practice it lead to a lot of confusion and interesting interactions with how to resolve triggered effects due to pausing one batch to resolve another that by the time Sixth came they scrapped Interrupt speed altogether (merging it into instants) and just had the much simpler stack system.
  • The batch rules where such that all damage, not just combat, would be resolved after all other spells and effects in a batch, including damage from said spells and effects. This was due to how damage and damage prevention was resolved back then as separate phases in the batch. This lead to things such as trying to kill a creature being targeted by Giant Growth using Lightning Bolt failing no matter if it was played before or after Giant Growth since the damage would be resolved last anyway, making the entire thing pointless. Changing to the Stack system fixed this by having noncombat damage being applied when its effect is resolved, and damage prevention effects acting as shields and Regeneration effects activate beforehand.
  • Even after the changes to how damage resolves combat damage was still put on the stack. This caused a lot of rules headaches and loopholes. Because damage goes on the stack (and thus locked in), it allowed players to do things like sacrifice their own attacking or blocking creatures to activate effects while the damage they would deal would still go though, and most infamously caused the massive headaches that was calculating Trample damage. It took till Core Set 2010 for them to finally remove damage on the stack to finally close the sacrifice creature loophole and make trample far less of a headache.
• Want to give a would-be rules expert a headache? Ask about the interaction between Humility and Opalescence. Several of the relevant rules were invented to make this one specific situation less mind-bendingly confusing.
• The Shadows over Innistrad set introduced a double-faced card, Startled Awake, that's a sorcery on one side and a creature on the other. (It can be put onto the battlefield transformed as a creature from a graveyard.) The problem is: What if some effect now transforms it? It would be a sorcery card on the battlefield, which is nonsensical. A previously existing rule states that a sorcery cannot enter the battlefield, but that doesn't cover this case, because transforming is not entering the battlefield. Instead, a rule was added that if there's a sorcery (or instant) on the other side of the card, and an effect tries to transform it, it simply doesn't transform.
• Wizards' policy of not errata'ing for balance reasons came to a head with the introduction of the 'Companion' mechanic in Ikoria: Lair of Behemoths. A Companion card could be placed in your sideboard and played from there for their normal mana cost, any time you wanted, provided your deck adhered to certain deckbuilding restrictions such as "every permanent card in your deck has converted mana cost 2 or less." The cards were looked at with skepticism before release, only for that skepticism to turn to horror very quickly when it was realized that these cards were extremely strong. Their effects were certainly powerful, but the fact that the core mechanic allowed you to essentially start with a free card that you could play any time was so invaluable that many of them saw heavy play in a variety of formats. Two of them, Lurrus of the Dream Den and Zirda, the Dawnwaker, were very quickly banned in Legacy and Vintage as their requirements were extremely light for those formats, and bans for Standard were expected to come. Faced with the very real prospect of having to ban a significant number of them in many formats, Wizards made the unprecedented decision to nerf the entire mechanic via an errata, changing it to simply allowing you to draw the card into your hand for 3 mana rather than play it for its cost. Even still at least one Companion (Yorian, Sky Nomad) still sees play in Standard.
  • Lutri, the Spellchaser was preemptively banned from Brawl on release, because the format rules rendered the companion restriction moot, meaning any deck using red and blue could run it with effectively no drawback at all.
• There used to be rather game-breaking combinations of cards owing to a quirk in the rules regarding life. Upon the initial release of Magic, a player would only lose the game if they had zero life at the end of the current phase. This allowed players to spend more life than they had to cast super-powerful spells, then crafting some sort of other card combo to bring their life back above zero before the current phase ended. The rules were eventually changed so that a player loses instantly when their life hits zero, shelving these card combos.
  • However, a stipulation is that all damage and lifegain is calculated instantaneously, rather than in order, so that if you have 10 life and take 10 damage, but get 2 life from Lifelink, you don't lose, but instead end with 2 life points.
• Meant to deal with trolling attempts similar to Maik S.'s saga on the Yu-Gi-Oh! page (and possibly inspired by him in particular), Magic requires that the player be able to shuffle their deck, using only their hands, in a reasonable timeframe (as decided by the judge, who may also get a proxy for the player if they're disabled). It's 250 cards in the online version Arena, which has no physical limits because the computer handles the shuffling; however, doing it online means it's harder to troll the other player, and a 250-card deck is going to be incredibly bad unless it's trying to pop Battle of Wits (which isn't in Arena anyway).
  • Similarly, while there is no theoretical limit to the number of tokens you can create from spells and effects, there is an upper limit of sanity. For games in person, the limit is usually defined by the tournament (or just space restrictions, or the number of tokens you can actually produce), but for Arena, the maximum number of tokens is 250 as a hard cap, which already causes the engine to freak out. If an ability would create a token but you've already hit the max, the token just isn't created, and you lose any benefit (if a token creature would enter the battlefield and cause you to gain life, the token isn't created, the creature does not enter the battlefield, and you don't gain life, for example).