Nkuba, whose name is the Nyanga word for lightning, is the celestial divinity of the thunderbolt and one of the chief supernatural powers of the epic. Answering Mwindo's summons, he descends in seven lightning strokes to destroy the hero's foes and to shatter the fortifications of Tubondo. Yet the relationship is double-edged: the dragon Kirimu is Nkuba's cherished companion, and when Mwindo boastfully kills it, Nkuba seizes the hero and bears him into the sky, where the celestial beings drive him through burning heat and freezing cold until he abandons his arrogance. Nkuba thus embodies both the aid and the discipline that heaven extends to the over-reaching hero.