The best thing about being a troll shaman is that you're easily the coolest type of character in the game. Who else can switch between weapon fighting and both combat and support casting as easily as they want? And rather than merely duplicating the skills of complimentary professions, the shaman has a very unique set of abilities that give him an identity all his own. So it's not just that the shaman is part fighter, part mage, part priest. It's that the shaman has entirely unique abilities that allow him to fill any of those roles with ease.