DLC 1 had some interesting maps, but nothing all that exciting (that I remember - haven't played any of DLC 1 for a couple months or so). DLC 2 introduces the gold ants & silver spiders - MUCH tougher versions. DLC 2, mission 16 is by far the best farming level in the entire game. DLC 3 is pure challenge. Some of the maps on it are utterly insane. Still need to finish that one.