In the area of the Upper Orinoco River in Venezuela, Yanomami shapori (shamans) engage in hostile acts against their colleagues and people (especially children) living in distant villages in order to inflict misery and death. These combative magical practices are primarily motivated by retribution for past assaults of a similar kind. While in most cases the shapori perform these activities intentionally, this article argues that the malevolent non-human acts are also driven by the cannibalistic nature of hekura spirits, which demand human souls. In this way, although shapori intentionally engage in bellicose activities, they must sometimes kill in order to appease the ancestral spirits and thus spare the lives of their own kin. This article focuses on the dark side of Yanomami shamanistic practices in order to counterbalance tendencies that emphasize the more positive, therapeutic aspects of shamanism, namely, its socially integrative roles.