Gamble

The cheapest unconditional tutor in the game, and the discount comes entirely from a drawback that combo decks learned to manage. For one red mana you fetch any card in your library, a rate normally reserved for tutors costing three or four; the balancing friction is the random discard, which fires after the search resolves. That ordering is the whole design, and the probability runs against you in a way that is easy to misread. Because the tutored card joins your hand before the discard, every other card in your grip is a body shielding it: the more cards you already hold, the likelier the random pitch lands on something else. An empty hand is the worst case for protecting your target, because that target becomes the only legal card to discard. Decks that lean on Gamble therefore split into two camps. The first holds a healthy hand so the discard scatters harmlessly across cards they didn't need. The second tutors for something they're happy to throw away (a reanimation target, a flashback spell, fuel for graveyard recursion) and treats the discard as a free trip to the yard rather than a cost. Red has almost no other access to library tutoring, which is why a card with a genuine downside has endured for a quarter century: it is the color's only real door to consistency, and the players who run it have spent that long learning which side of the gamble they're actually playing.