Fool's Hat

This extraordinary hat comes to several points, each with a bell affixed to it. A number of times per day equal to your Charisma modifier, you can snap your fingers as an action and become _invisible_ . The invisibility lasts until the end of your next turn, and it ends early if you attack, deal damage, cast a spell, or force a creature to make a _saving throw_ . However, the sound of bells jingling means your location is always known if you use any movement.

Source: Level Up Advanced 5e · OGL-1.0a · 5.1