BakuMutation is a rare series of Bakugan. They were in the B3 series. All Bakugan in this series are literally half one Attribute and half Clear. They were not released in the United States besides the people who won SpinMaster's Bakugan Contest. They have a special ruling unique to themselves: "They may take the opposing Bakugan's attribute if the opposing Bakugan is a Special Treatment Bakugan".