Citadel of Smoke (Stonehaven League #4) by Carrie Summers

This is the showdown that has been building as Devon and her
allies fight to save Owen, both from a rogue computer entity and his own father’s
political game. To do so, Devon must strengthen her dark powers and descend
into the dimension of Hell and bring the fight to the evil Zaa and her band of
Demon Lords.
A futuristic look at online gaming that allows full
immersion into the gaming world. But when there’s a computer glitch, it creates
an enemy that can cause real harm to the players. There’s no escape. You must
fight. You must win!
Ms Summers once again shows that she is a master storyteller with a fantastic concept, suspense, massive battles, humor and the
talent to pull it all together.
Loving this series.