Darkkness

Life is perfectly ordinary for Fern Olsen until a spelunking adventure reveals something entirely unexpected: a portal to another world lies within a cave near her home, and the dangerous, otherworldly people who use it are taking an interest in Fern. An accident years before has left Fern in possession of all the magical powers of Darkkness, a world ruled by the infamous King Quoth. The power-hungry King wants to take over a second world, Lumina, but he needs to take the magic of his own world back from Fern to do so. Suddenly, Fern is thrust into a prophecy to save both Darkkness and Lumina from the King. Armed with power she doesn't understand and a slew of allies with questionable motives, she must stop the King before he destroys another world.