"Crystal Beast", originally named and known as "Gem Beast" (宝玉獣（ほうぎょくじゅう） Hōgyokujū) in Japan, is an archetype of 7 monsters with various Attributes (primarily EARTH and WIND) and Types (primarily Beast) that all share the same effect of becoming Continuous Spell Cards upon their destruction. Although they have low ATK and DEF, their aforementioned effects allow them to have great staying power. They are also supported by many cards as Continuous Spell Cards. When all 7 Crystals are either on the field or in the Graveyard, their boss monster, "Rainbow Dragon", can be Summoned. This archetype also contains one of the most powerful OTK setups with "Crystal Abundance", as well as sturdy control with the five effects of their Field Spell Card "Ancient City - Rainbow Ruins".