Costumes are outfits for Cookies that change their physical appearance. Costumes will occasionally change the appearance of their attacks as well. Costumes have no effect on stats and/or damage in any way, being a purely a cosmetic effect. There are currently three costume rarities, being Common, Rare, and Epic costumes. Some costumes are obtained through the Guild Shop or special event rewards, although most of them are only obtainable through the Costume Gacha that was introduced in the Too Hot to Handle Update. To pull in the Costume Gacha, the player must spend 300 Rainbow Cubes per draw. If the player pulls a costume that they already own, they are instead rewarded with Rainbow Crystals that can be used to purchase unowned costumes in the Rainbow Crystal Exchange. (For more information regarding the Costume Gacha, see Costume Gacha.)
There is a permanent event featuring a draw tutorial where the player can obtain a guaranteed copy of 
GingerBrave's GentleBrave's Tuxedo costume as well as some Rainbow Cubes to use in the Costume Gacha.
There are currently 28 equippable Costumes in game. When Costumes were released, the game featured 17 equippable Costumes.
