Yorick, Shepherd of Souls

When Yorick, Shepherd of Souls enters the battlefield, create a 5/5 Black Legendary Spirit Horror Token named "The Maiden of the Mist" with Shroud and "Whenever a non-token Creature dies, create a 1/1 Black Mist Walker token"
Yorick gets +X/+X where X is the number of Mist Walkers you control.