Throne of the Ancients (Stonehaven League #6) by Carrie Summers

This is it! Demon War!
Ms. Summers delivers the goods. The build up to the Demon
threat climaxes in an all out, winner take all, fight to the finish. Devon must find some weapon that can take on
the Demon army that is literally at the gate of Stonehaven or they lose all.
But she’s juggling a hundred details including a dead friend, losing her food
supply, the safety of her people and a betrayer in her party.
This story just flies and Summers once again shows why she
is such a talented fantasy writer. This series keeps getting more exciting.