When I use to play World of Warcraft, Catalcysm, Mists of Pandaria and Warlords of Draenor had not been released. Each expansion had to be deliberetly purchased.
I am getting back into the game, but on a new account. I am aware that purchasing a new copy of World of Warcraft also gets me all the expansions, up to and including Mists of Pandaria.
My question is this: Would an old, unused expansion key count? If I upgrade my account with a key from Wrath of the Lich King, will it count as the full upgrade to Mists of Pandaria? If not, what would happen?