Sunburst was tasked by Starlight Glimmer to find a way to control the Windigos so they could be used against the tyranny of the Storm King. Unable to find a viable solution, in a desperate move, he found a way to unite the essences of the Windigos with the essence of someone else, but that essence had to be from someone immaterial, and the only being that came to mind was King Sombra. By making a deal with him to rule the Crystal Kingdom again, she got him to the resistance and fused him with the Windigos. This gave him the ability to summon them and use their magic at will.