The Trolls of Blackwater Deep: Book three of the Kings of Pendar

The trolls have returned to Pendar, not to destroy the walls, but seeking the aid of King Edward this time. Wilgar, the high priest of the trolls has sent the General Armagh as an emissary requesting King Edward’s help to defeat an invader of Blackwater Deep. A dagar, a demon of fire, is laying waste to the troll’s city that lies deep within the roots of the mountain below the ancient dwarven stronghold Drogheda.
King Edward, answering the call, marches his army of dwarves deep into the mountain to try and help an old ally defeat the demon, but what they discover along the way changes their mission to one of survival with no guarantees that any will make it back home.