Magic Key World
Magic Key Worlds are randomly generated worlds accessed by a Magic Key in Dragon Quest Monsters 2. When a Magic key is obtained, it's destination is unknown. The Key Appraiser in the Key Shop in GreatLog can identify them, giving them a name. The first part of the name indicates how rare the monsters encountered in the Magic Key World will be. From least to most rare, the names are Ylw, Plain, Green, Blue, First, Red, White, Quiet, Black, Gaudy, Silvr, Dream, Misty, Secrt, Shiny, and Last. The second part of the name indicates what sorts of monsters can be found there. Each world contains monsters from one or two monster families. Worlds containing a single monster family are rarer than two-family worlds.
Magic Key Worlds have several different landmasses, each of which has a boss. The bosses of individual islands are found in shrines, with a stronger boss residing in a castle. Monsters cannot be recruited on an island until that island's boss has been defeated, and none of the boss monsters can be recruited. None of the ??? family can be recruited. Towns and additional dungeons appear in the worlds, as well, with the dungeons usually having new Magic keys or accessories at the end.