Abhorsen — Garth Nix

Orannis the Destroyer has been freed and only Lirael, newly come into her inheritance as the Abhorsen-in-Waiting, has any chance of stopping it. She and her companions--Sam, the Disreputable Dog, and Mogget--have to take that chance. If Orannis's unspeakable powers are unleashed, it will mean the end of all Life. With the help of her companions and a vision from the Clayr to guide her, Lirael must search in both Life and Death for some means to defeat the Destroyer--before it is too late...