Girufadomu Barusuruku is a forbidden spell that Riou can use. It transforms Riou into a huge monstrous being, which Banikis calls his "beserker" form. In this form, Riou has no control over himself, attacking allies and enemies alike, therefore he tells Banikis to run away after casting the spell. His strength in this form was never truly shown because he was still overpowered by Zeon.