Might be worth expanding on that small “dubious distinction” tidbit some.

Magic, having such a massive card library, has multiple formats. One of them, Vintage, is designed to allow as many of them as possible. Overpowered cards are not banned, just “restricted” to a single copy (rather than the normal four). Black Lotus? Go for it. Ancestral Recall? Not a problem. Vintage does have some banned cards, though.

All 25 of the Conspiracy cards are banned, as they are in all constructed formats - these were from a pair of draft-focused special sets, where having cards that literally just gave you something free didn’t hurt the balance because it meant giving up a chance at another card (btw Conspiracy Draft is a really fun, I highly recommend it if you can find a box, or add some conspiracies to your Cube if you’ve got one).

Nine cards referencing “playing for ante” are banned, because they run afoul of gambling laws. When the game was first invented, Richard Garfield thought it needed more stakes, and also more ways for cards to change hands (card shops didn’t exist at the time). So after drawing your starting hand, each player would “ante” the top card of their deck, removing it from the game, and the winner would take home both cards. Some cards were made that interact with this - for example, Contract From Below lets you draw a new hand for one black mana, but you also have to ante another card. These cards are banned in every sanctioned format because ante is no longer even an option in sanctioned play, because that could make it qualify as gambling which has all kinds of legal headaches that just aren’t worth it. (There is a very interesting “steal every card your opponent owns” combo, using Tempest Efreet, that would be possible if these cards were allowed.)

Two cards using physical skill are banned. Chaos Orb and Falling Star had the player flip the card onto the table, and had an effect on any card it touched. This made players place their cards far apart, so only one at most could be hit, and with the size of board state you can get in Magic, that caused problems at tournaments with people running out of table space. And they’re not that great anyways, so nobody really misses them.

The last banned card is Shahrazad. The card isn’t all that great - you start a new game of Magic, and whoever loses that game loses half of their life total in the main game. But if you can win the subgame, you could win the main game just as easily, so it’s kind of pointless if your intent is to win.

But it takes time. With a slow, control-type deck, especially one designed to do so, a match can easily last half an hour. And even if Shahrazad were restricted to a single copy, there are ways in the game to copy a card’s effect multiple times. Now imagine playing ten subgames, each taking half an hour. Most people would rather forfeit than deal with that. And in a tournament with time limits, odds are pretty good the main game is still at 20-20, so it would be a draw. You can go pretty far in a tournament getting only draws and forfeits.

And that’s why Shahrazad is one of thirty-seven cards that are not allowed in any game of Magic. It’s just that un-fun, in the wrong hands.

In the right hands though, it can be a blast. Two similar joke cards have been made, for the not-competitive-legal Un-Sets. Enter the Dungeon, from Unhinged, instructs you to go under the table and play a subgame starting from 5 life instead of 20, and The Countdown Is At One, from Unstable, has you play a subgame starting from 1 life. (Both of these cards are also not legal in Vintage, but not specifically banned. Rather, the cards were printed with a silver border, marking them as not-even-allowed for any official format... although they’re a blast for casual play and I recommend anyone who isn’t an obnoxious tryhard to give Unstable a chance).