The Sinister Minister; one of my favorite commons in Dissension, the fact that he does amazing work in both Blue and White puts him over the top. Stinkweed Imp recursion giving you a headache? Just tap the sucker down. He even combos with cards like Sky Hussar for the double tap. Simple, elegant, logical design, in short, one of the many cards that puts Ravnica Block in a league of it's own.