Quote from Senturafun fact: i've read that scandinavians in more northern parts used to have their reindeer eat amanita muscaria, so they then could drink the piss of that reindeer. the idea was that the reindeer would filter out all the toxins because they're more resistant to it.
it's a bit weird that they (vikings) would bother to use muscaria when it's mostly a deliriant and produces a much less lucid state than the even more available psilocybe semilanceata (which they also used). perhaps the analgesia made it easier for them to berserk. and perhaps the believable hallucinations made them think they really were at the gate of asgard participating in the most epic battle ever. there's really no limits to the suggestibility of delirium... (or psychedelics for that matter)
i'm hoping we will see some of it in the series. the introduction scene where he hallucinates valkyries was pretty cool.
didn't mythbusters debunk this? fairly sure one episode they have too much of the mushroom and were deemed unfit for fight due to stomach ache and shit. as far as these legends are willing to go, i'm more inclined to believe that their rage was natural
did they prepare it? (drying and/or boiling) that would remove the toxins and make it easier to digest without getting stomach ache. anyway, the mentioned semilanceata is much easier on the stomach and shouldn't have given them too much problems. they could have used the piss-method i mentioned.
i don't think they necessarily did it for rage, but to give a more spiritiual/religious experience during battle. as you probably know, fighting and dying on the battlefield was the most glorious and spiritual aspect of their life. it could also help them to deal with the fact that they might die. still, i agree that the effects (maybe excluding enhanced/sensitive senses) could easily have made it a lot more difficult for them.