The Republic of Thieves by Scott Lynch 

With what should have been the greatest heist of their career gone spectacularly sour, Locke and his trusted partner, Jean, have barely escaped with their lives. Or at least Jean has. But Locke is slowly succumbing to a deadly poison that no alchemist or physiker can cure. Yet just as the end is near, a mysterious Bondsmage offers Locke an opportunity that will either save him or finish him off once and for all. Magi political elections are imminent, and the factions are in need of a pawn. If Locke agrees to play the role, sorcery will be used to… Read more.