River of Magic — Thom Nichols

After the giants arrive, it is only a matter of time. No one understands them. No one owns them. The only thing to do with them is to go to war. It takes a surprisingly short length of time to destroy the world. Now, as the world recovers, the only thing to do with them is to destroy them. Magic, madness, and saber tooth squirrels stand in the way as a thousand years of pain and deceit prevent their destruction. It might take a little treachery and a lot of luck to turn the tables.