Bloodring (Enclave Series, Book 1)

the long version

No one thought the apocalypse would be like this. The world didn't end. And the appearance of seraphs heralded three plagues and a devastating war between the forces of good and evil. More than a hundred years later, the earth has plunged into an ice age, and seraphs and demons fight a never-ending battle while religious strife rages among the surviving humans. Thorn St. Croix is no ordinary neomage. All the others of her kind, mages who can twist leftover creation energy to their will, are gathered together into Enclaves long ago. There, they live in luxurious confinement, isolated from humans and exploited for their magic. When Thorn's powers nearly drive her insane, she escapes--and lives as a fugitive, disguised as a human, channeling her gifts for war into stone-magery and the pacific tasks of jewelry making. But when Thaddeus Bartholomew, a dangerously attractive policeman, shows up on her doorstep and accuses her of kidnapping her ex-husband, she retrieves her weapons and risks revealing her identity to find him. And for Thorn, the punishment for revelation is death ...