Spy Glass (The Chronicles of Ixia, 6)

New York Times bestselling author Maria V. Snyder develops a world of molten magic where a magician's powers can remain hidden—or even be lost… 

After siphoning her own blood to defeat her enemy, Opal Cowan has lost her powers. More, she's immune to the effects of magic. Opal is now an outsider looking in, spying on those with the powers she once had, powers that make a difference in her world.  

Until spying through the glass becomes her new power. Suddenly the beautiful pieces she makes flash in the presence of magic. She also discovers that someone has stolen some of her blood—and that finding it might let her regain her powers. Or learn if they're lost forever…