Ice Walk.  The dragon can move across and climb icy surfaces without needing to make an ability check. Additionally, Difficult terrain composed of ice or snow doesn't cost it extra movement.

Storm aura. The dragon causes a blizzard to swell up around it in a 30ft sphere the area is lightly obscured.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., 1 target. Hit: 15 (2d10 + 4) piercing damage plus 9 (2d8) cold damage. 

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., 1 target. Hit: 11 (2d6 + 4) slashing damage. 

Blizzard breath.  The dragon exhales an icy wind in a 40-foot line that is 15 feet wide. Each creature in that area must make a DC 15 Constitution saving throw, taking 36 (8d8) cold damage, or half as much damage on a successful one. Creatures must also make a DC 15 Strength saving throw or be pushed 30ft by the strong winds

Storm aura surge (Recharge5-6). The dragon causes a blizzard to surge up around it, the blizzard becomes heavy obscurement and all Creatures in the aura must succeed on a DC 15 Wisdom survival check before moving or move in a random direction. The surge lasts until the start of the dragon's next turn.