Psychoactive drugs

Vikings used these psychoactive drugs to prepare for battle. The people who used them were called the Beserkers. The drug put them in an uncontrollable rage and allowed them to feel no fear of pain, injury and death. As a result, these fierce warriors would not back down when injured because they were completely numb to pain and the killing that they were doing. This became lethal and let alone terrifying as they were in a violent and murderous mood.