Bone Raptor

Ambusher In the first round of combat, the bone raptor has advantage on attack rolls against any creature it has surprised.

Death Sense the bone raptor always knows the direction of an undead creature within 1 mile.

Death Eater If the bone raptor makes an attack against an undead creature, it can make an additional bite attack against that creature as a bonus action.

Hooked Claws At the start of its turn, a creature grappled by the raptor takes 2d6 piercing damage.

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

Necrotic Adaptation Its hitpoint maximum cannot be reduced

Pounce If the bone raptor moves at least 20 ft. straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 12 Strength saving throw or be knocked prone. If the target is prone, the bone raptor can make one bite attack against it as a bonus action.

Pack Tactics The bone raptor has advantage on an attack roll against a creature if at least one of the raptor's allies is within 5 ft. of the creature and the ally isn't incapacitated.

Multiattack. The bone raptor makes three attacks on its turn: one with its bite and two with its claws

Bite . Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 2) piercing damage. 

Claw . Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 2) slashing damage.