Over the nearly 30 year history of Magic: The Gathering, there have been game-breaking cards. Here's a story about one of them.
Appropriately accelerating land drops in Magic can be a bit of a dance. In the early years of the collectible card game, multiple different things were tried. The card Land Tax was one such attempt.
The year is 1994, and the newest expansion was Legends. (Magic Untapped has a short video about the set on YouTube).
The set introduced many things, including multicolored cards and a new white enchantment designed to help players hit their land drops.
Land Tax was originally made to discourage players from destroying lands, as Legends would have some mana intensive cards in it. But by overbalancing there, it opened up a new avenue for players to take advantage of.
At the very low cost of one white mana, the enchantment conditionally allows its controller to search their library for as many as three basic land cards and put them into their hand. The condition? An opponent simply having at least one more land in play than you do.
It doesn't seem like it at first glance, but for someone with extra land it essentially allows you to pull a bunch more cards than you would have before. Add to that cards like Scroll Rack, which can turn those lands in your hand into other cards off of the top of your deck, or Ivory Tower or Zuran Orb to turn those lands into life gain, whether in your hand or on the battlefield.
It's no surprise that this little one mana card ended up breaking Magic for a good while in the mid 90s.
In the end, Wizards of the Coast wound up banning the card in the then-equivalent of Standard and Vintage/Legacy in July of 1996, and in Extended in July of 1998. And in Sept. of 2004, when Legacy became its own format separate from Vintage, the card remained banned there, too.
For years, that was it. Eight years, in fact, as in June of 2012, Wizards of the Coast decided to un-ban the card in Legacy, causing an eventual snowball affect for the card. As of today, it's legal to use in all formats that allow the card, such as Vintage, Legacy, and Commander.
Despite its age and power creep in the game, Land Tax can still be a pretty powerful card even if it's not nearly as widely played these days as it used to be. Still, it carries a noticeable price tag ranging from around $30 for the Battlebond and Double Masters printings to as much as $90-ish for the Judge promo.