The statement that is NOT true of a Viking berserkr is:
They were the leaders of the Viking tribes.
Berserkr were typically warriors known for their ferocious fighting style and often fought in a trance-like state, but they were not necessarily the leaders of Viking tribes. Leadership roles were more commonly held by chieftains or other figures of authority. The other statements, while somewhat exaggerated or simplistic, reflect characteristics or cultural associations related to berserkers.