Vaca

Dark Feast. The wendigo can consume enough of a dead or unconscious Humanoid in 18 seconds (3 rounds) to fully heal itself.

Improved Critical: The Wendigo's attack does a critical hit on the rolls of 19 and 20. 

Territorial Pursuit. The Wendigo can sense any creature that is within 1 mile of it as long as that creature is on the same plane of existence.

Spellcasting. Vaca is a 5th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 16, +3 to hit with spell attacks). Vaca has following Necromancy spells prepared:
Cantrips (at will): Spare the Dying, Chill Touch 
5th level: Raise Dead, Danse Macabre 

Mimicry. The Wendigo can perfectly imitate any animal sound  or humanoid voices it hears, as loudly as it wants. Wendigo can emit a call for help or sounds of wild game to bait it's prey away from the group or settlement. If possible, Wendigo tries to stalk a group to learn voices of it's members before luring them to their doom. Though, in desperation, wendigo can confront a group head-on. In such case it tries to stun as many enemies it can with it's roar, snatch most defenseless member of a group and retreat to a safer place to murder and devour it's victim.

A creature that hears the sounds can tell they are imitations with a successful DC 20 Wisdom (Insight) check.

Regeneration. Vaca regains 2D12 hit points at the start of its turn if it has at least 1 hit point. If the wendigo takes fire damage , this trait doesn't function at the start of the wendigo's next turn.

Flight. The Wendigo can fly and will drop its prey from the sky to inflict maximum damage.

Lost Senses. Vaca removes all sense of smell from anything within 45ft, and reduces sound heard by anything nearby, imposing disadvantage on any perception checks made against it.

Multiattack: The wendigo makes three attacks: one with its bite and two with its claws. If it can it will use a Gore attack instead of a Claw attack.

Bite(Devouring Flesh). Melee Weapon Attack: +10 to hit, reach 5 ft., 1 target. Hit: 16 (3d6 + 6) [piercing] damage and 1d6 necrotic damage. The wendigo bites a chunk off its prey and swallows. It regains hit points equal to necrotic damage dealt.

Gore. Melee Weapon Attack: +10 to hit, reach 5ft., 1 target. Hit: 19 (2d12 + 6) [slashing] damage. If the Wendigo succeeds on two Gore attacks in the same round it will attempt to slice the target in two.

Claw. Melee Weapon Attack: +5 to hit, reach 5ft., 1 target. Hit: 15 (3d4+6) [slashing] damage. If the Wendigo is able to land 2 claw attacks, it will try to grapple the creature. The opposed creature has imposed [Tooltip Not Found] and must succeed on an Acrobatics check DC 18.

Silence. As a bonus action, Vaca can invoke the silence spell on up to 5 creatures it can see for 18 seconds (3 rounds) 

Confused Victim. As a reaction to a tougher prey, Vaca will mimic a sound through its mouth without opening it and create a illusory echo with a 60ft radius of a loved one or mate of its prey in danger, the creature must make a DC15 Wisdom save or instantly abandon its turn and run towards the projected illusion

Vaca has 3 Legendary actions that it regains on the end of it's turn

Devouring Claw Attack (Costs 1 Action). Vaca can make a claw attack dealing an additional 10 (3d6) necrotic damage on hit. it gains that much temporary life.

False Mimicry. Vaca can feign a mimicry attack, with silence coming out of its mouth targeting up to 3 creatures, +5 to hit, on hit, creatures effected take 8 (3d4) psychic damage as an echo rips through their ears.