Akai Oni Masuku (Red Oni Mask )

A demon like mask made of wood, it looks like it is fragile, but it is as hard as diamond. Used by many and drove many to insanity, this mask wields terrifying powers, if you attune to it, before wearing it, you have to drop at least one blood drop in the mask otherwise it will be stuck in your face until you satisfy its blood thirst, while attuned to it, you can write and read Infernal, your alignment turn to Lawful and Evil and it grants +2 on AC. 

Demonic Aging. You start to age less often, 100 years is equal to 1 year to you.

Terrfying Gaze. As an action, you can cause all creatures in a circle of 60ft. radius centered on you, make a Wisdom saving throw, otherwise they will be frightened by you for 1d10 minutes, you can't use this festure again until you finish a long rest.

Oni Gaze. As an action you can make one creature you can see to implode in bursting eerie blue flames, it must suceed on a Dexterity saving throw CR 18 taking 4d6 fire damage on a failed save or half as much on a succesful save, he is now lit on fire and takes 5 fire damage each turn he is still on fire, he can make an Constituition saving throw CR 13 to get rid of the flames. You can't use this feature until you complete an long rest.

Demonic Resistance. You have resistance to peircing, slashing and blugeoning damage caused by nonmagical weapons not made of adamantine.

Darkvision. You can see in dim light within 60 ft, as if it were bright light, and in darkness as if it were dim light.

Soul Eater. When you kill an enemy, the mask absorb its soul, giving to you 1d10 temporary hit points

Nightmare Slash. As an action, you run 30ft, your sword blade turn pitch black and cold as ice, hell fire hurl from it, make an Attack with advantage, every enemy that is 5ft. away from where you passed takes the damage, if you hit, double your damage, add +2d10 necrotic damage and he has to succeed on a Wisdom CR 20 check, otherwise images of true terror appear on his mind and he takes 4d10 psychic damage, or half as much on a succesful save. You can't use this feature until next dawn, if it fails on the save, it is now paralized

Soul  Offering. Every day you wake up attuned to the mask, you take 2d10 necrotic damage.

Curse. If you are attuned to it for at least 1 week, your apearence starts to transform. Your skin starts to turn grey, your teeth grow and two horns grows on your head and on the course of weeks, your face gets an apearence like the mask,you also gros claws that can be used to make an attack dealing 1d6 + your Strength modifier, your Charisma score is reduced by -3. The curse can only end by a Wish spell if the mask user wants it.

Destroying This Item. You must handle the mask to an entity of Good and Lawful alignment to take it to the positive energy plane and destroy it, doing so, the old user of themask has the curse removed and it reforms in another place of the material plane.