A Girl of Stone & Smoke - Daughters of the Volcano, #1

Book One in Daughters of the Volcano Her destiny is fire.and death. Since seventeen-year-old Aera's holy powers manifested three years ago, she has known nothing but the temple, the priests, and the long training to make her into a fire priestess. Everything about her former life she has had to forget, even Corus, childhood friend and the boy with whom she was beginning to fall in love. Able to transform her body into molten rock, she is destined to serve the volcano god forever, as lava-shifter, priestess.and executioner.
Before she takes up her ordained role, she must face her final test. Execute a criminal sentenced to death for the most unforgivable of all sins: blasphemy. But it's no anonymous lawbreaker waiting chained at the centre of the labyrinth. It's Corus, sentenced for the crime of being a gargoyle, a winged stone-shifter. A gift akin to hers.except his gift is unsanctioned by the temple, his powers proclaimed unholy.
If she refuses the test, she will betray her god and condemn her family to disgrace. To pass it, she must kill the boy she loves. 21, 000 words