Realms of Shadow (Mondragoran Chronicles)

After averting Armageddon, Jordan Hanson thought life would get easier, but in fact it was just the opposite. While he'd successfully driven away the world-destroyers, the Mondragoran, countless dimensional portals had been torn open in the process. Now, Jordan found himself continually dealing with dangerous creatures entering our world, while trying to hide this new reality from the general public. For the most part, Jordan felt that he, with the help of his powerful friends, had a handle on things. Then something very ancient and angry found its way back to Earth--something that felt the world would be a much better place with far fewer humans on it....