We've outlined a number of ways to screw around with the rules of Magic over the years, all viewable under this heading if you so desire. The thing is, most of these exist in the realm of the purely theoretical - the type of circumstances that would only ever line up if some little stinker deliberately set out to do so. Fun to think about, but not the type of thing that will ever come up in an actual game.
Today, however, we're going to look at a bit of a rules snafu that is of particular interest because it is a situation that can easily happen in a real Magic tournament: it involves two cards that are both played regularly!
So first, we have Brainstorm. It's played quite a lot based on how powerful and versatile it is, but the effect is fairly simple: draw three cards and then put two back. Then you have another card played in Legacy quite a bit, and that's Sylvan Library.
The Library is something you might need to consider for a minute, seeing as it has had a few changes in wording over the years. As is often the goal (I hope,) the most recent oracle text makes it pretty clear how the card operates. You draw two extra cards during your draw step, and then of all the cards you've drawn this turn (which should usually be three, seeing as you have your normal draw step plus the two extra from the Library) you have to put two back or pay 4 life apiece to keep the extras. Again, a strong card, but not too tricky to understand.
Now, the problem is that these two cards interact in an odd way that may not be immediately apparent. If you have a Sylvan Library in play and then cast a Brainstorm during your upkeep, you will have to call a judge over to resolve this part of the turn. Yeah, no kidding. This is because Brainstorm permits you to put ANY two cards from your hand back on top of your library - they need not be from among the three cards Brainstorm drew you. Because of this, it could potentially be strategically important for an opponent to not know whether a card you put back is one you just drew or already had in your hand.
But then, when Sylvan Library triggers, you draw two extra cards and have the option to put any card you drew this turn back on top of your library. Normally this wouldn't be a big deal since those cards will generally be the usual plus the two extra from the library. However, the cards you drew from Brainstorm are also cards you drew this turn. So now it suddenly can't be clear whether or not a card you're placing back on top is one you drew with Brainstorm earlier in the turn. Because of this, you have to call a judge over solely to watch your hand of cards and confirm you aren't cheating, which is fairly ridiculous.
