when attuned to this crown and waring it your proficiency bonus for all CHA skills is doubled and you get advantage on checks made to persuade or intimidate.

If a intimidation check is more than double the creatures CHA skill then they are frightened until they can succeed a CHA saving throw (DC is the wearers  CHA skill)

Notes: to properly attune to it a creature must slit their hand and let the blood soak into the crown