Masks

Boss Masks are vanity items dropped by all non-event bosses, and also from the Old One's Army bosses. They are worn in the social head slot. Each boss has a 14.29% chance to drop its own mask.

Trivia

 * Although most event bosses (e.g. Ice Queen, Santa-NK1, Pumpking, Everscream, Mourning Wood, Flying Dutchman, Martian Saucer) will not drop a mask, they will still drop their respective Trophies.
 * The mask dropped by the Lunatic Cultist is called an Ancient Cultist Mask, rather than Lunatic Cultist Mask.

History
보스 가면 Masque 面具