Wondrous Item, rare (requires attunement by a worshiper of a moon deity)
Even when the moon disappears its presence is still felt in the world. Crafted during a rare blue moon, this brooch provides its wearer with similar opportunities to vanish or be obscured. Stylized to look like a full moon with a gentle blue glow surrounding it, this brooch also gives off a low harmonious hum that only the wearer can hear when its magic is being used.
The Brooch of the Blue Moon has 5 charges and regains 1d4+1 charges every sunset
Notes: worshiper of a moon deity
Hey, uh... you never said anywhere what the charges are for.
From the website where they were originally posted: