This mask doesn’t appear to have a strap holding it in place on your face. It has one red half and a blue half, with the red half featuring a star in place of an eye and the blue half displaying a rhombus.
This mask appears invisible when you first attune to it and place it on your face. When you speak the command word as a bonus action, it materializes on your face.
While the mask is active, you have advantage on saving throws against being charmed or frightened. If you already have advantage against these conditions, then having this mask active makes you immune to the condition.
While active, the mask radiates an aura of happiness to your allies within 30 ft. of you and can see you. Allies within this range, including you, have resistance to the first instance of damage they take before the start of their next turn. Additionally, your allies’ Charisma score increases to 14 if their score was lower before the effect.