The Viking Berserkers were known to have consumed special mushrooms found in Yggdra forest before battles that apparently would "slow" time for them, remove pain, and give them a rage so powerful they could smash their enemies into oblivion.
There is actually many stories about them in Nordic lore.
For example the lone Berserker who defended a village from approximately 40 enemies on the villages only entrance which was a bridge. Although the Berserker died at the end of the battle (His arm was lopped off near the end of the battle but continued to cut enemies down despite the minor flesh wound) with his final words being "now the village is safe".