In all seriousness, I feel like any deck with Progenitus needs a way to get it out of the hand because if you draw it all of a sudden you have 3-4 dead cards in deck. Outside of Brainstorm, how do you get rid of Prog once you draw him?
Wild Mongrel, discard it, gets reshuffled, problem solved. Not only that but the Mongrel is a green card as well so able to being sacced.