Diablo's skill system has been revamped countless times in the 12 years since Diablo 2, and Martens believes the system we're getting in Diablo 3 is the best Blizzard has yet created. "Our goal is to make something that's easy to understand, but sort of disarmingly complex by the time you've mastered it," he said.
The game offers new skills and other features as you progress, "so that you always have something new you can do," Martens said. "It's sort of hard to make a mistake. It's easy to redo. You can choose to change your skills at any time so you can lock into something that works for the way that you play the game."