"The Well of Ascension" A Mistborn Novel by Brandon Sanderson

The impossible task has been accomplished. The Lord Ruler has been vanquished. But with Kelsier dead, too, the awesome task of building a new world has been left to former street urchin and Kelsier's protégé Vin, who is now the most powerful Mistborn in the land. Vin is now worshipped as a hero in her own right, but she is haunted by a strange vaporous entity hidden in the mists.