A Quest of Earth and Magic — S. Usher Evans

Their quest was just the beginning Queen Ayla has ascended the throne, but finds her kingdom in tatters after years of deception. She is eager to reopen the lines of trade and alliances with the other kingdoms, but all they want is her hand in marriage and the power of the Pennlan stone that comes with it. Her heart is conflicted, especially as the knight Ward draws ever closer to her. When a troll arrives in Pennlan inviting her to visit the mysterious realm, Ayla sees a golden opportunity to open trade with another race of magical creatures without needing to marry anyone. Not only that, but the trolls profess to have another piece of the seod croí-and Ayla is eager to strike up an alliance with them before anyone else does. She summons home her best friend, the wizard Cade who had been continuing his magical training under the watchful eye of the fae. But the trolls don't just invite Ayla. Riona is also summoned, hoping to rebuild bridges burned a thousand years ago. And when they arrive in the troll kingdom, they find things might not be as easy as they'd hoped. The second book in the Seod Croí Chronicles takes readers back to Pennlan for another journey full of twists and turns.