Wendigo, the Ancient Hunger

Legendary Resistance (3/Day). If the Wendigo fails a saving throw it can choose to succeed instead.

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. 

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

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

Natural Disturbance. A Wendigo can cause intrusive thoughts, hallucinations, or force creatures within 200 feet to look through it’s eyes at will, often viewing themselves or their group from a distance. If the creature can physically see the Wendigo, it can no longer influence them in this way.

Known Territory: The wendigo can sense any creature that is within a mile of it as long as that creature is on the same plane of existence.

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

Regeneration. The wendigo regains 20 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.

Abyssal camouflage. When the wendigo is 25 feet or more away from another creature, it is invisible to them until the start of the wendigo's next turn.

Pounce. If the wendigo moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 16 Strength saving throw or be knocked prone. If the target is prone, the wendigo can make one bite attack against it as a bonus action.

Scent of Fear. All creatures within 50ft have disadvantage on Wisdom saves.

Wendigo Curse: If a creature lands the final blow on a wendigo they must succeed on a DC 16 Wisdom saving throw or feel an overwhelming need to consume the flesh of the dead beast. If a creature does so it will slowly over the course of the following D6 weeks feel an increasing need to feed off of human flesh. If it does so it will transform into a wendigo and become a creature under the DM's control. A remove curse spell may end this effect.

Multiattack. The wendigo makes two claw attacks. Alternatively, it can make one with its bite and one with its claws instead.

Claws. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit:  15 (3d6 + 5) slashing damage plus 5 (2d4) cold damage. 

(Bite) Devouring Flesh: Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 15 (3d6 + 5) piercing damage and 10 (3d6) necrotic damage. The wendigo bites a chunk off its prey and swallows. It regains hit points equal to necrotic damage dealt.

(Bite) Feed The Hunger: Melee Weapon Attack: +11 to hit, reach 5 ft., one grappled humanoid. Hit: 16 (2d10+5) piercing damage, plus an additional 14 (3d8) cold damage. The wendigo gains temporary hit points equal to the damage done. While the wendigo has temporary hit points, it cannot use this attack again.

Cannibal's Bite. Melee Attack: Uses affected creature's weapon attack modifier to hit. Hit: 16 (2D8 + 7) piercing damage.

Inflame The Hungry. (Recharge when no creature is affected by this power). Ranged, 50 ft., targets one creature. Target must make a wisdom saving throw DC 16. On a failure, the target takes 22 (4D8 +4) psychic damage, or half as much on a successful save. If it fails to make the save it is also dominated by the wendigo as though under the effects of a Dominate Person spell. While under the wendigo's control the target may only make a single Cannibal's Bite attack during its turn against a target of the wendigo's choosing.

Primal roar (recharge 5-6): The wendigo lets out a terrifying roar that inspires fear in all that can hear it. Creatures that can hear must make a DC 16 wisdom save or be frightened of the Wendigo. They may attempt the save again at the end of each of their turns. Creatures who save are immune to this effect for 24h.

Feeding Frenzy (1/day): Ranged attack, targets all creatures within 50ft of the wendigo that are not at maximum HP. All creatures targeted by this attack must make a DC 15 charisma saving throw or be forced to take a Cannibal's bite attack against a target of the wendigo's choosing. If no targets are close enough, the wendigo can force a creature affected by this power to use it's reaction to move close enough to another target and make the attack. If a creature fails by 5 or more, it is also dominated as though under the effects of the Dominate Person spell.

Speed of the Starved: The wendigo moves up to its speed without provoking opportunity attacks.

Abyssal Creature. The Wendigo is an abyssal being that does not exist in the real world fully. Because of this they can enter the ethereal plane as a reaction thus avoiding an attack entirely and causing a single attack that would otherwise hit to miss.

 The Abyssal Wendigo has 3 Legendary actions that it regains on the end of it's turn.

Primal Roar. (2 Action) The Wendigo Releases a horrid Scream.

Claw attack. (1 Action) The Wendigo Attacks with a claw attack.

Speed of the Starved(1 Action) The Wendigo moves up to its speed without provoking opportunity attacks.