A mask of frightful facade is a mask crafted to look like a fearsome monster. The DM chooses what creature the mask was designed to resemble, and the challenge rating of that creature determines the mask's rarity. 

As an action, you can don the mask to transform into the creature it resembles for up to 1 hour or until the mask is removed. The transformation otherwise functions as the shapechange spell, except that it requires no concentration and you can't assume a different form.

A creature within 5 feet of you can attempt to forcibly remove the mask by making a Strength (Athletics) or Dexterity (Acrobatics) check contested by your own (Athletics) or Dexterity (Acrobatics) check.  If the creature wins the contest, it prises the mask from your face, causing you to immediately revert to your normal form.  A creature must be aware of the mask's existence to attempt to forcibly remove it.  A detect magic spell reveals the mask's existence and properties.

Once the mask has been used, it can't be used again until the next dusk.

Notes: Social, Combat, Shapechanging