And the Unicorn You Rode in On by Robert Jeschonek

An elf cowboy on a fool’s errand to the Old West town of Desperation, Arizona hunts a faerie bandit queen with a powerful relic in her clutches...but his unicorn steed faces the greater test. The one-horned magical stallion pursues the runaway love of his life, a chase that pits him against brutal men and beasts alike. What he finds at the end of the trail will change his fate and that of the Wild West forever.