Northern Storm is a skill located in the Winter's Embrace (which can be found in the Warden skill tree). Northern Storm is an ultimate. Northern Storm is a morph of Sleet Storm
Northern Storm deals the following types of damage: Frost Damage. Which means that it gets buffed by the following blue champion point trees: Elemental Expert, Elf Born, Master at Arms, Spell Erosion. Also the following red champion point trees protect against this skill: Elemental Defender, Iron Clad.