Player customization for optional flavor: The mask can appear in any menacing form but for simplicity’s sake we will say it’s base form is a dear skull mask, but can be implemented in the form of Glasses, a Ring, a malicious glint in the eye, or other bodily item the represents the item and is approved by both player and DM

The wendigo mask is an ancient artifact coming from an unknown source and passed from owner to owner through violent force of will.
It possesses a great and horrorable power!

DM’s Optional choice: Whoever wears the mask is looked down upon socially by everyone(party can be included), disadvantaged on charisma saving throws

When an owner of the mask is killed or dies it calls out phyconically to beings within a 200 foot radius supernaturally drawing them in unknowingly against their will.

When any being is within a 30 foot radius of the mask well it isn’t currently equipped by another living being they are faced with a primal desire to put on the mask.

^Any player that wants the mask is able to approach and equip the mask without any need to roll a dice and will automatically attune to it.

If no player wants the mask All players must roll a D20 minus your highest proficiency bonus from your primary stat, the player with the lowest score must equip the mask. After each longrest the player wearing the mask has an opportunity to attempt to remove the mask rolling a D20 against the DM who does the same. If the Player rolls higher than the DM they are given free will to disregard the item as they please, potentially giving it to another player in their party, selling it to a merchant or individual who’s aggressively willed to put it on, or even leaving it in a public place to become a potential reoccurring plot point later. 

Well the mask is Equipped the player receives a natural bonus to dexterity and a bonus to intimidation if they previously did not possess a bonus to intimidation.
Additionally the player wearing the mask feels a deep primal urge to eat anything that they have dealt the killing blow to.   
The player wearing the mask is able to Eat or consume (pieces, majority, or all) of ANYTHING that they have dealt the “killing” blow to including elemental, mechanical, and undead entities, ect. 

Roll to resist the urge via D20 roll against the dm. 
The higher roll determines who decides how things play out. 
If the player consumes any amount of flesh from a being they got the last hit on they receive up to a maximum of one token per combat instance and cannot go above one token at any point. 
The bonus provided by spending the token goes to your classes primary attacking stat and is based on the size or difficulty of the last thing consumed to gain a charge>1(small or weak creature), 2(medium creature), 3 (large or powerful creature), 4(massive or Boss creature)  
The token can be spent immediately after rolling initiative to increase your primary attacking stat during the instance. Whether or not you have a token doesn’t affect your urge to consume your victims after you’ve killed something.

Notes: Bonus: Dexterity Score, Advantage: Intimidation, Bonus: Ability Score Maximum, Natural Weapon: Slashing, Immunity: Frightened, Roll higher than 8 on a D20, Cursed