I recently completed Nightmare difficulty of Dragon Age II. It was one of the most painful experiences I've had recently, largely because there's no concept of balance with the difficulty for the most part. When I want difficulty in an RPG, I tend to aim for the type that encourages careful management of my party, proper preparation, and patience rather than blind luck. Maybe throw in a healthy dose of trial and error. Some battles in the game managed to meet these requirements. The (SPOILER)High Dragon optional boss in Act III, for example, was exactly the type of thing I was looking for. The (SPOILER)Rock Wraith boss at the end of Act I, on the other hand, was well as a number of other optional bosses near the end of the game, were a lot more about blind luck than actual difficulty. When a boss can kill your entire party (which was very well equipped within two seconds of spawning, that's not hard, that's stupid.