Crown of Fire: Forgotten Realms: Shandril's Saga, Book 2

Adventurer on the Run! Once Shandril was a humble kitchen maid. Now she's one of the most powerful magic-users in the land. And a lot of people want her dead. The evil Zhentarim, the powerful Cult of the Dragon-all of them want her spellfire, and they'll kill whoever they must to get it. There's only one thing for Shandril to do: run. With the aid of Elminster of Shadowdale, the Knights of Myth Drannor, her lover, and a determined dwarf, she'll wield her magic for the cause of good. But if her magic becomes too powerful, her friends won't have a choice.