Oh the Legendaries - One of my favorite DLC for Borderlands 2,
This review is from: Borderlands 2: Mister Torgue's Campaign of Carnage Add-On Campaign Pack (Software Download)
These will work on Mac steam versions of Borderlands 2 unsure if it works on the version you buy from the Mac App store. To activate on steam got to the game in the menu bar and click "activate product on steam."
I think of all the DLCs this is the best especially if you want to farm legendary weapons. First the Torgue vending machines have every Torgue Legendary that you can buy with easily farmable Torgue Tokens. So if you want to get some nice weapons this is by far the best DLC.
Plus there is Pyro Pete the new raid boss who is super easy to farm & drops TONs of Legendaries. It may be "short" by some accounts but it is great for the great gear you can get.