The Wendigo uses Wisdom as its spellcasting ability.
Mimicry. After observing a creature for one minute, the wendigo acquires supernatural insight and has advantage on Charisma (Performance) checks to imitate the voice of someone the target knows. This ability lasts until 24 after the Wendigo last observed the target. Keen Smell. The wendigo has advantage on Wisdom (Perception) checks that rely on smell. Wendigo Fever. Creatures struck by the Wendigo must make a DC 14 Constitution saving throw. On a failed save, they must spend their actions to attempt to remove their clothing & armor as quickly as possible. This doffing occurs at the following intervals for armor category:
Multiattack. The Wendigo can make two claw attacks and a bite attack on its turn. Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., Hit: 12 2d8+4 piercing damage. On a hit, the target must succeed on a DC 13 Constitution saving throw or take an additional 9 2d8 necrotic damage. Claw. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 10 (2d8 + 4) slashing or piercing damage plus 3 (1d6) cold damage. Maddening Feast. The Wendigo feasts on the corpse of one enemy within 5 feet of it that died within the past minute. Each creature of the Wendigo’s choice that is within 60 feet of her and able to see her must succeed on a DC 15 Wisdom saving throw or be frightened of her for 1 minute. While frightened in this way, a creature is incapacitated, can’t understand what others say, can’t read, and speaks only in gibberish; the DM controls the creature’s movement, which is erratic. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the Wendigo’s Maddening Feast for the next 24 hours.
The Wendigo may take 1 legendary action, 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 its turn. Detect. The Wendigo makes a Wisdom (Perception) check. Move. The Wendigo moves up to half its speed.
The region containing an Elder Wendigo's lair is warped by the it's magic, which creates one or more of the following effects:
A wendigo that has eaten many meals grows not only in size but also in malice. Stag-like horn growths appear on its head, its ribs burst out of its chest, and its once humanoid skull transforms into that of a deer-like shape, its skin and eyes gone. Wendigos are already a force to be reckoned with, but with time and food they can dominate entire landscapes.
Arctic, areas of supernatural cold, any lands experiencing winter.