In the summer of 1996, one card completely upended decks across Magic: The Gathering's competitive scene.
In 1996, Magic started the Pro Tour off with Pro Tour #1, held in New York in February of that year. While competitive Magic nowadays has a lot of stop gaps in place to prevent one specific card or style of deck to get too popular, there wasn't much in place back then besides the rules and a ban list, with the latter still being a newer concept. As the tournament showed, one type of deck did ridiculously well - Necropotence decks.
Necropotence decks themselves had only come into being a few months before when the card was introduced in the Ice Age expansion. Basically, you could rig up a deck to not only draw three times as many cards as your opponent, but also make it so you don't lose any life in the process, with Necropotence being the central card in the deck.
Magic R&D did know that this could happen, and there was already a card out there that could easily block it - Black Vise. Basically it could erase life very fast the more cards in a hand. That was the danger of Black Vise.
The problem was that Black Vise was placed on the ban list right before the New York tournament. Necropotence, once easily blocked...was now allowed to be free. For the rest of 1996, and especially during the summer tournament season, top players either had a Necropotence deck or an anti-Necropotence deck, with the latter requiring numerous cards working together to kind of act as a Black Vise. But make no mistake - Necropotence was THE card at the center of it all. Pretty much every Tour of Nationals winner had one deck or another, with other popular deck styles at the time falling by the wayside.
Eventually, card rotation and new ban rounds undid this, with the inaugural 1996 Pro Tour being held as a lesson for acting quicker to ban cards and make course corrections as quickly as possible.
Today, whenever Wizards announces a new ban mere weeks or even days after the release of a new expansion, it can all be traced back to the summer of 1996, which has since been called 'Black Summer'. Wizards of the Coast does not want another Necropotence situation on their hands ever again, and quick bans and favored deck monitoring nips these problems in the bud before they can become a major problem.
Usually.
