I think this book has something to do with Dungeons & Dragons, but the basic set up is that the Hadron Collider malfunctioned and all of the infinite universes (multiverse theory) converged and combined to create an apocalyptic world where all of these universes overlap.
The main girl has nanobots that can eat metal through her skin and she can shoot out like a gun, along with some other tricks that I can't fully remember. Her guardian/partner is this humanoid buffalo.
I think a "silver-surfer" type alien shows up near the middle or end but I am not certain.
As for when it came out, the only thing I can say is that it came out before 2012 for certain, and it must have been within 5 years of that, though I am not certain of that part. I say this because I first found it at my local library when in high school, and I remember it being a new adition to the library's catalogue at the time.