Amulet of Asami (The Legendary Relics Series) (Volume 1)

Elysia a young royal mage, Rafe a young shape-shifting warrior, and Maeron a elven assassin of thief blood are at the yearly matching festival preparing to be formally matched in a proper triad, but so is the dark overlord. They get thrown into an adventure of ancient Power and prophecy to seek out the ancient relics of the founding Mage, Warrior, and Thief to save the world before it is taken from them.