Wendigo

Legendary Resistance (3/day). When the Wendigo fails a saving throw, it can choose to succeed instead.

Surprise Attacker. The Wendigo has advantage on attacks against creatures with the surprised condition.

Keen Scent. The Wendigo has advantage on perception checks that rely on smell.

Regeneration. The Wendigo regains 10 hit points at the start of its turn. If the Wendigo takes fire damage, this trait doesn't function at the start of the Wendigo's next turn. The Wendigo dies only if it starts its turn with 0 hit points and doesn't regenerate.

Fear of Fire. If the Wendigo takes fire damage, it has disadvantage on attack rolls and ability checks until the end of its next turn.

Mimicry. The Wendigo can mimic the voice of any humanoid they’ve eaten previously in an effort to lure pray into traps. A listener can make a DC 18 Wisdom (Insight) check to discern that something is off-putting and wrong about the sound, though they are unable to glean the nature of this unsettling feeling.

Heart of Ice. Being near the Wendigo comes with an unbearable cold. If a creature touches the Wendigo or hits it with a melee attack from within 5 feet, the creature takes 7 (2d6) cold damage. Further, a creature that ends its turn within 5 feet of the Wendigo must make a DC 18 Constitution saving throw or take 3 (1d6) cold damage.

Multiattack. The Wendigo uses its Terrifying Scream and makes one bite and two claw attacks.

Bite. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 17 (2d10 + 5) piercing damage, plus 13 (4d6) cold damage.

Claw. Melee Weapon Attack: +11 to hit, reach 10 ft., 1 target. Hit: 15 (2d8 + 5) piercing damage.

Terrifying Scream. The Wendigo lets out a bloodcurdling shriek that threatens even the hardiest of minds with shattering terror. All creatures within 30 feet must make a DC 18 Wisdom Saving throw. On a failure, they take 13 (4d6) psychic damage and are frightened for 1 minute. If the creature is within 10 feet of the Wendigo and becomes frightened, its speed is reduced to 0 ft. A creature may attempt the saving throw again at the end of each of its turns. 

Devour Whole. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. The Wendigo attempts to get at its one, true desire: flesh. If a creature within 5 feet is at 0 hit points, the Wendigo can spend the turn feeding on it. The creature dies immediately, and the Wendigo grows stronger. It heals for half of the creature’s hit point maximum and has advantage on attacks and saving throws for the next minute.

The Wendigo can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The Wendigo regains spent legendary actions at the start of his turn.

Desperate Speed. The Wendigo moves up to its speed without provoking opportunity attacks. If it ends this movement out of sight, it can make a stealth check as part of this action to hide.

Claw. The Wendigo makes a claw attack against one creature within range.

Night Howl (Costs 2 Actions). The Wendigo uses its Terrifying Scream.