Wendigo

Growing Hunger. as a curse this starved lust for hunger, may never end. Whenever the wendigo consumes Sister Flesh it instantaneously diffuses into their mass. never filling alway needed more. After eating enough bodies the wendigo size increase by one(see Rip off a morsel) Each time does this it gains a legendary action & can reapply its frightful presence  Both of which it uses intstaly. Furthermore in gains an addition Hit & Hp Die to its attack and health. its range increase by 5ft & its targets by 1. Finally it regains a legendary resistance 

Frightful Presence. Each creature of the Wendigo choice that is within 20 feet of the dragon and aware of it must succeed on a DC 15 Wisdom saving throw or become frightened for 1 minute. 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, Repeating only on certain traits 

Verable Skin. the Wendigo has taught invulnerable skin infused with its bones. However it attacked with Fire, it loses its natural Armour & resistances 

Legendary Resistance (2/Day). If the Wendigo fails a saving throw, it can choose to succeed instead

Multi-Attack. the Wendigo can make two attacks, one with is claws & another with its bite

Claw. Melee Attack: +8 to hit, reach 10 ft., 1 target. Hit: 10 (2d6 + 4) [Slashing] damage. 

Bite. Melee Attack: +6 to hit, reach 5 ft, 1 target. Hit: 12 (2d8+4) [Piercing] damage. The Creature must Con Save(Dc14) or will regain hp equal to damage dealt. & gain 1/2 Value towards Growing Hunger 

Devouring Breath. RangedWeapon Attack: range 10/25 ft., 1 target. Hit: 6 (2d4+2) [Necro] damage. Constitution Saving Throw(Dc14) or suffer a point of exhaustion  

Claw. Melee Attack: +8 to hit, reach 10 ft., 1 target. Hit: 10 (2d6 + 4) [Slashing] damage. 

Rip off a Morsel. When a creature fall unconscious, The wendigo can move Half its movement and make a Melee attack if in reach. Doing so in auto kill the creature as in consumes it. Assimilating its mass to its own. For a rough guide the Wendigo grows after consuming a certain amount of total bodies. [large=1](Huge=3, Giant 6) [huge=6] [Giant=27] [Gargantuan=180] [Monolith 3000]

The Wendigo has 3 legendary actions. it can use after another creature ends it turn Regaining at the start of its next urn  

Devouring breath (Costs 2 Actions). The Wendigo Can make its Devouring breath attack.

Bite (Costs 1 Actions). The Wendigo Can make one Bite Attack

Rip off a Morsel (Costs 1 Actions). The Wendigo can make its Reaction attack as a legendary action with the movement If its in reach.

Reconstitute Skin (Costs 1 action) The Wendigo can Reactivate its Resistances