Angelos Odyssey: Volume One - Angelos Odyssey, #1

Thousands of years have passed since the Earth was invaded by gods, demons, and foreign species with capabilities far beyond that of most humans. Reality collapsed, disaster having become so widespread that hope was ultimately forgotten. Humankind was backed into a corner and forced to either evolve or submit to forces far beyond them; the world erupted into a never-ending war that resulted in new cultures, superior technology, and great division among living beings.
This is the story of the most ambitious assassin, Tavon, whose ambition drove him to explore past his simple upbringing in the slums of the Citadel in order to become one of the most notorious killers in the universe.