Shahrazad

The most notorious rules-text on any card from the game's first year, and the only card whose effect requires you to shuffle up and play a second game of Magic before resolving the first. Mark Rosewater has called it the card he most regrets, and the DCI's response was eventually total: Shahrazad is banned in every sanctioned format, a distinction shared with almost nothing else in the game. The design problem is structural rather than mechanical. Two white mana is a trivial cost; the subgame is not. A single resolution can extend a tournament round by half an hour, and a recursive Shahrazad (one cast inside the subgame, then another inside that) produces a tree of nested games whose terminal nodes are not guaranteed to halt within the time limit. The life-loss clause, which reads as the punchline, is almost incidental: the real cost the card imposes is on the clock, on the judges, and on every other match in the room waiting for a pairing. It is the canonical example of a card whose power level on paper bears no relationship to the reason it cannot be allowed near a tournament, and the case study every developer learns from when a mechanic asks the players to do something the format itself cannot absorb.