So here's a cheap but effective way to kill the Ferelden Frostback in the Hinterlands even if you're several levels lower than it. Equip your mage with a frost staff, then run across the battlefield when the fight starts and tuck them behind the rocks near the smugglers' dock. Then just autoattack the dragon til it's dead, tossing in the occasional energy barrage if you wish. Once all your other party members are down, the dragon may frequently shoot fireballs at you, but they'll hit the rocks in front of you. In this case, the dragon never shot fireballs at me, did its flying around shenanigans, or even summoned dragonlings. It just sat there like lump getting hit by my attacks.