This item does not have much mechanical impact, but has so many interesting uses in the role playing context!
Description:
This amulet alters a being's appearance to match their emotions of the moment, with extreme exaggeration. Someone in a rage would be horrific and hideous, while someone fearful would make them appear weak and sniveling. This is like many other cursed items, it can't be removed without use of remove curse spells or effects.
Tips:
One interesting twist can be that there is no curse to the item, and playing up the effect can be quite beneficial or hurtful to role playing encounters with mundane people or beasts, using their appearance to control the encounter. (Boo!) Also, causing an NPC or creature to appear to be what they are not can let the party think they are some ghastly beast, when they are merely a goblin with a cursed amulet. Think of all the interesting ways something like this can inject some more role in your regular game you play!