A Protocol for Monsters — John Birmingham

The much anticipated companion volume to Emergence, the story of Dave Hooper's superhero embiggening. When an oil rig drills too deep under the Gulf of Mexico it breaks the capstone separating our world from the UnderRealms - home to monsters, daemons and dark magiks. The nightmares of our long ago come flooding back into the world where they are met by automatic weapons fire, heating seeking missiles (they're hell on dragons, don'tcha know) and one drunken, dissolute son of a bitch called Dave.
But this is not Dave's story. This is the story of the poor bastards who had to put up with him while he saved the world and acted like a jerk.