The pearl saga Volume 3
The Cage of Nine Banestones

Kundalans face their darkest hour since the V'ornn invasion one hundred and one years ago. Their prophesied saviour bas finally been incarnated, in the body of a young woman, named Riane. But a secret society of outcast sorcerers are plotting her downfall, having gathered together eight ancient banestones. Each stone is a source of immense malevolent power, but if the sorcerers find the final missing stone, all nine together will form an engine of unimaginable destruction, bringing doom to Kundala and all of her inhabitants...