Chad Rebmann 
Power of the Valkyrie #1 [EPUB ebook] 

As an Elysian war rages onward and spills upon the Earth, an ethereal gift is all that stands between the dark minions of Hell and their malignant conquest of the Heavens. An unlikely protagonist, Suzanne Bancroft is a single nurse at a small Colorado hospital who only wants to live a safe and sheltered life. However, she has been chosen to hold the key to both heaven and hell in the palm of her trembling unsure hands.