The Seven Deadly Sins are mini-bosses that can be encountered on any floor in their respective Mini-Boss rooms outside of The Chest and Dark Room. Unlike with bosses, there is no special door leading to a mini-boss room, meaning that there is no way to tell whether a room is inhabited by a mini-boss unless the player has an item that reveals map icons such as Compass or a Map item. Once in a mini-boss room, the player cannot escape through means of bombing the door, as it will be boarded off. The Sins and Super Sins notably become tougher the later in the game they are encountered.
Each of the Sins has specific drops, that are consumables or a pedestal item (less frequently). In a room containing multiple Sins, only the last one will drop something, allowing you to choose what drop you want by killing a certain mini-boss last.