Black Fire

The sky flashed red as Syfrid flew toward the ground, and Calron quickly followed. The two brilliant criminals were exiled from their home world and sent crashing to a new planet, where they were quickly captured by the powerful city of Esgrathia, a city armed with unrivaled weapons. This new world is ancient to them—even the weapons of Esgrathia are little more than antiques—and the pair long to leave it. Their only chance to redeem themselves and return home lies in helping the humans avert a disaster that could befall their world. Fortunately, the pair have arrived on the brink of catastrophe. 
A man long thought dead is seeking Black Fire, the most powerful weapon in the world. If he obtains it, unimaginable destruction will ensue. Calron and Syfrid must stop him, and the army of goblins they soon discover he commands, from destroying Esgrathia and the kingdoms of humanity: Rathin, the Red City, Orthon, the City of Stone, and Karthac, the City of Darac.
However, as the pair traverse the world they discover the dark history behind the current conflict, and must decide what role they should play as civilizations clash and ancient battles resume.