Keen Hearing and Smell. The undead winter wolf has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Pack Tactics. The undead winter wolf has advantage on an attack roll against a creature if at least one other undead winter wolf is within 5 feet of the creature and isn't incapacitated.

Snow Camouflage. The undead winter wolf has advantage on Dexterity (Stealth) checks made to hide in snowy terrain.

Undead Fortitude. If damage reduces the undead winter wolf to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the undead winter wolf drops to 1 hit point instead.

Undead Nature. The undead winter wolf doesn't require air, food, drink, or sleep.

Multiattack. The undead winter wolf makes two attacks.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage.

Cold Breath (Recharge 5–6). The wolf exhales a blast of freezing wind in a 15-foot cone. Each creature in that area must make a DC 12 Dexterity saving throw, taking 18 (4d8) cold damage on a failed save, or half as much damage on a successful one.