Definately a frost troll. Took me a few tries to get past it. You have to play hit and run

first I used my full magicka (100) with frostbite on him. Then I did the fire breath shout. And then just keep hitting him when he is dazed, "when he get's back to the world", just wait for him to smash and try to evade it by running away but with him in your view. And then you can rush in and hit him maybe once, maybe twice or more. Level 12 when I tried it with a steel sword (19 dmg) and an iron shield (24 block I think). It was a hard fight, had to do it multiple times till I found a hard way to kill it.
Not forget to mention, sometimes it does hit you, then I used my healing spell
