The Guardians of Rhea. The Rhean Chronicles, #1

Sara is a Guardian, an elite human warrior trained to battle the races of Rhea, but she soon finds herself on a quest to save them when their afterlife is invaded by a powerful, mysterious race called the Pelasgians. In the journey that follows, she will see a side of the Rheans never before seen, and discover that the Pelasgians are a much greater threat than anyone can imagine. Vampires, mummies, werewolves and other creatures of mythology are reimagined as various races who must join forces to confront an ancient evil.