In the official dungeons of Infinite Paradise, when players trigger and complete side or hidden quests in dungeons of Hard level or above, they may obtain a special item—a Magic Box.
Of course, Newbie Dungeons and hidden dungeons players find in the real world don't count.
There are four grades of Magic Boxes: white, blue, purple, and gold. Opening a Magic Box allows players to acquire an item of the same grade, be it equipment, an item, or a Skill Book. As for what they'll actually get, that depends on the player's luck. The highest-grade gold Magic Boxes might even contain attribute points.
Of course, this is just one of the Magic Box's functions. If you don't trust your luck, you can also use it as currency.