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

Pack Tactics. The wolf has advantage on attack rolls against a creature if at least one of the wolf's allies is within 5 feet of the creature and the ally isn't incapacitated.

Undead Nature. The wolf does not require food, water, air, or sleep.

Undead Fortitude. If the wolf is reduced to 0 hit points, it must make a Constitution saving throw with a DC equal to 5 + the damage taken. On a success, the wolf drops to 1 hit point instead.

Multiattack. The wolf makes two attacks.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d4 + 5) piercing damage and 5 (2d4) necrotic damage.

Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (1d6 + 5) slashing damage and 7 (2d6) necrotic damage.