J.M. Briggs 
The Iron Trishula [EPUB ebook] 

A call from an ancient ally takes the mages to India. A Demon horde has found a way around the defense of the Iron Gates and is building an army to take over the Iron Realm. The Desai family, descendants of one of the past Iron Souls, welcome the mages with open arms, but how can Alex reconcile with an old family when she’s lost her modern one?

Lokpal was a warrior, trained from childhood to protect his home from the Demons who wander the land. Nothing prepared him for a god slipping into madness. When two strangers with magic arrive, he must navigate between his culture, his family, his beliefs, and the long-standing traditions the Grand Mages uphold if they have any chance of stopping the Demons.