Warbreaker - Brandon Sanderson

Meet WARBREAKER. This is a story of two sisters - who happen to be princesses, the God King one of them has to marry, a lesser god, and an immortal trying to undo the mistakes he made hundreds of years ago. Theirs is a world in which those who die in glory return as gods to live confined to a pantheon in Hallandren's capital city.

A world transformed by BioChromatic magic, a power based on an essence known as breath. Using magic is arduous: breath can only be collected one unit at a time from individual people. But the rewards are great: by using breath and drawing upon the color in everyday objects, all manner of miracles and mischief can be performed.