too bad you can't have a bit of blue, i think Blighted Agent would work wonderfully for you, especially if you had some Cavern of Souls so that it or some of your other infect creatures cant be countered on summoning
oh sorry for double post but i forgot to add that if you could muster a consistent source of blue you could possibly use Artful Dodge to have unblockable infect. However i think it would be touch stretchy incase you don't need the blue
4x Wild Defiance , no question.
Get rid of Revenge of the Hunted . Unless you top-deck it, you'll never get to 6 mana to cast it. Also dump Mirran Mettle (the Metalcraft]] will never happen) for card:Ranger's Guile, for removal-protection.