strazybm

So I got into a dungeon (Mana Tombs) with a level 71 Frost DK, and this guy was doing some absurd damage 1 shotting everything in his path. Was just wondering if anyone could possibly tell me how this guy was doing so much damage at this level https://gyazo.com/91f93df94d5a7df4fe78adf6b511b9ec https://gyazo.com/152b92b697241071a8c8e862acd2b5a0