Dragonslayer (Convergence #2)

The enemy unknowingly opened a portal to the Netherworld, and our world’s only wizard somehow managed to close it. Unfortunately, something got through. Something big. A dragon. Now Kaz Wolfe, with help from his dog Duke who is channeling the spirit of a wizard from ancient Babylon, and with no help from Azib the Cowardly Genie, must find the dragon before someone gets a cellphone video of the thing, and the world learns that magic is real. Or, you know, before the dragon eats someone.