The Season of Fear - The Calling Chronicles, #2

The destruction of Earth was just the beginning. Lazarus and his group of Alpha Mages have received a mission from Merlin. They must find him and the enchanted talisman, Excalibur, in order to save the world they once knew. But in the wake of apocalyptic destruction has come a plague. A race of mutants infects anybody who stands in their way, morphing innocent survivors into twisted monsters. No one is immune.
No one is safe. With humanity's last stand set to take place in Austin, Texas, Lazarus and his friends must find a way to save everything they hold dear from total annihilation. If you like the fantasy stories of Terry Brooks' Shannara Chronicles with the emotional impact of Stephen King's The Stand, then you will love The Season of Fear.