Monster cards are one of the two main types of cards in Dark Duels. They primarily used to reduce an Opponents LP to 0, though they may be used for other purposes, such as defending a player from being attacked directly. Additionally, the Special Abilities of some monsters can affect gameplay in ways that other cards cannot. In Dark Duels, many monster cards are able to be strongly upgraded through the use of support cards. This generally makes gameplay more intense, as a monster with less that 1000ATK can easily be increased to 2500.