The Shards of Orr is one of the hardest dungeons in EotN. The easiest way to get through to Gadd's Encampment is to bring Smiting Prayers skills, Dervishes with Avatar of Balthazar, and/or equip your weapon users with Heart of Holy Flame. Otherwise, you could try to simply run through avoiding the mobs. Near the last section of the dungeon are 3 mobs which are fairly hard to kill; flag your heroes and henchmen to create a distraction while you run through to the gate of the encampment.