Warfare was widespread in classical India. Although the Buddhists of India abhorred killing, they could not evade or ignore war altogether. From the seventh century to the thirteenth century, various types of war magic, together with justifications for their use, developed in tantric Buddhist communities. Defensive types of war magic adhered to pacifist ethics and aimed to avoid, halt, or disperse armies. Harmful war magic was applied in the context of the transcendent ethics of enlightenment. Even when warfare was fully incorporated into Buddhist soteriology, non-violence remained a paramount virtue, and the scope of a just war was very limited. The present survey of tantric sources shows that tantric Buddhist war magic emerged as a reaction to the inevitability of war and was applied in the hope of mitigating warfare's excesses.