In Khans of Tarkir, the current Magic expansion, there are 5 clans. One of these, the Mardu, uses Red, White and Black mana. It contains some of the best cards in the game, such as Sarkhan, the Dragonspeaker and Sorin, Solemn Visitor but these are mythic rare. You're unlikely to see a Mythic Rare in your cards, much less a good one.
Then again, sometimes, just once in a lifetime, this happens:
Looks like I'm playing Mardu this time.