Latvians are selling them in copious amounts. They mostly work as a stimulant - you don't feel fatigue, cold, heat, hunger, you feel energetic, pain sensation is reduced, in other words there's a reason why berserkers took them before battle. Last time I drank some of that magic potion I took a hand scythe and cut the grass for about an hour or so. So you can imagine what a guy on that stuff can do if, say, instead of a scythe he's holding a big viking battle axe >:D