Do you mean the Mask of the Shapeshifter? That allows, once per long rest, to change appearance to another random character. Effectively a Disguise Self cast.
There's also the dagger that's 4-7 weapon. But I replaced that before I even dealt with the goblin camp. There's so many magic items I wasn't worried about it.
The biggest coup is the hat and cape. They offer no bonuses but they look so fly I'm probably never taking them off.