Epic rarity (Purple) versions of the Fire Oni Mask and the Void Oni Mask can be found when looting standard and Rare Chests ...

You can find oni masks in several places in Fortnite Chapter 6 Season 1, depending on the rarity you’re looking for. Epic (purple ... boss and is carrying the mask). Night Rose drops the ...

If you go this route, you will be able to find the purple epic versions of the masks. If you can find a legendary treasure chest, you increase your chances of finding an Oni Mask exponentially.