The Wong and Mystique combo amplifies Doom, Iron Heart and Spider Woman's abilities. Magik's limbo ability adds a good surprise (and wiggle room). Supporting cards like Uatu, Mojo and, The Punisher helps in dictating where your opponent will put his/her card.
Big trouble if you are fighting a deck with the Enchantress, Cosmo and Professor X -- but still a decent deck if you'll ask me.