The enemies from Amid Evil come in the different sets, with each of them residing in one World. These sets are made from four tiers of enemies + one boss. These tiers can be determined mostly by the durability of the enemy and their size, but also by their threat level. These tiers are as followed: Easy, Medium, Big and Huge. Not every set of enemies contains enemies for each of the tiers given. The earliest worlds, for example, lack huge enemy-types, and the later ones contain no easy enemies. Every World has exactly one boss included.