Dark World

Dark World is a series of Dark Fiend-Type monsters based around effects that activate when they are discarded from the hand to the Graveyard. However, this does not include cards that require you to discard as a cost, such as "Magic Jammer" and "Tribute to the Doomed". The names of Dark World monsters are color puns (with the irony that Darkness is devoid of color), except for "Reign-Beaux", which is a pun on rainbow. (It is pronounced as "Rainbow")