Mystery Chest Gold has the Baby Black Dragon in there, for 180RC each. You will have some low rates of getting them. Currently, the best boxes to get them from are from the boxes mentioned above. The item cannot be acquired permanently, and can only be acquired in timed versions. It gives 150% Bonus Carats (2.5x) while in games. It consists of stats shown below : SP +100 STR +3 ARM +2 CRI +10