Lei-Shen was one of Warcraft's most underrated antagonists of all time. Granted, they didn't give him more details until Chronicles but goddamn did they hype this man up. They even said in an interview that if was Lich King vs Lei-Shen that Lei-Shen would win if its 1 on 1.
Fun Fact: Because I have to mention Rexxar or else I'll physically die. I thought that Jaina was gonna unleash the power of Lei-Shen finally on the Horde and Rexxar would stop her by breaking her staff. But in the cost losing Misha. It'd be a sad day.