White Out

A water elementalist boss found in the north of Jaga Moraine slightly south of Frostmaw's Burrows. He is located at the top of a horseshoe bend. Has the Elite Skill Shatterstone. When you approach the hill a giant snowball will spawn and roll down the hill. Whiteout will then appear with an Avalanche.

He needs to be killed as a part of the Anything You Can Do quest.