Be the leaf. And I was. I waited patiently by the fireplace, sipping whiskey and reading Tolstoy for six weeks until “The Legend of Korra” premiered online for its fourth “book” (i.e., “season”). “The Legend of Korra” is the sequel to Nickelodeon’s original series, “Avatar: The Last Airbender.” In a world where “benders” are able to control one of the four elements. The protagonist, Aang, struggled to embrace...