Yes, this is a rogue set with a dress. And yes, you can just as easily pick the same model but as pants instead if you’d prefer. But we thought it would be cool to use the kilt version instead. The whole theme is basically a venomy theme, especially with the shoulders special effect. The mask was cool because it looks like its protecting the rogue from the poisoned shoulders or whatever.
Most of this set is pretty easy to get, but the mainhand dagger will require you to raid Illidan in Black Temple. The kilt can be found off a rare named Blazewing in Mount Hyjal or if you haven’t already done the Stonecore quests, one of the rewards gives you one too.