Wizardoms: Eye of Obscurance by Jeffrey L. Kohanek

Power. The ambitious thirst for it.
In a realm where wizards rule, those able to claim a throne are granted the power of a god.
How can one defeat a god?

A clever thief, a determined acrobat, and a troubled dwarf are joined by an old storyteller as they attempt the impossible: Assassinate a wizard lord. Their slim hope relies on an enchanted amulet, the Eye of Obscurance.

These unwitting pawns are embroiled in a contest of wizards. The stakes: The fate of the world.