Wendigo

Mimicry. The wendigo can mimic the voice and cry of animals and victims it has eaten in the past, it uses these to attract new prey. Characters familiar with the voice or the language will realise it is not their voice by passing a DC 13 Wisdom (Insight) check.

Ambush. On the first round of combat, the wendigo has advantage on attack rolls against a creature that hasn't taken a turn yet.

Death screech. On its first turn, the wendigo makes a high-pitch sound that all creatures within a 50 feet radius can hear. The creatures that hear this sound must succeed a DC15 constitution saving throw or have the deafened condition, any creature can gain advantage in this throw by covering their ears, additionally, creatures that hear the screech must also succeed a DC17 Wisdom saving throw or have the frightened condition. At the end of each of their turns creatures can choose one condition and end it by repeating the corresponding saving throw.

Multiattack. The wendigo makes two strikes with its claws, and then feeds.

Claws. Melee Weapon Attack: +8 to hit, reach 10 ft., 1 target. Hit: 9 (1d6 + 5) slashing damage.

Feed. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 18 (1d12 + 7) piercing damage. If the attack deals damage, the target must pass a CD 16 Constitution saving throw, or lose maximum hitpoints equal to the damage dealt, witch return at the end of a long rest. A character whose maximum hitpoints are zero is dead.

Fast eating. inmediately after tacking the feed action, the wendigo can take its bonus action to regain 2d8 +2 hitpoints. it cannot regain more hitpoints than those that the feed action took from the attacked creature. If a creature is killed by the "feed" attack this feature takes place without expending the bonus action.

Natural stalker. The wendigo can take the hide action as a bonus action.

Fast escape. When surrounded by 3 or more creatures within attack range the wendigo can take a reaction to move up to his speed without creating oportunity attacks.

Deathly antlers. When an attack roll hits against the wendigo, it can take a reaction to move its head towards de incoming attack, adding +3 to its AC, potentially causing the attack to miss.