Berserkers are humans with a reckless disregard for their own safety, who charge into battle and fight until death.
A berserker's battle-lust makes them completely fearless, and allows them to attack twice per round.
Large berserker groups are lead by war chiefs, fighters of significantly high skill, and their sub-chiefs. Berserkers disdain arcane magic, and so do not employ wizards in their leadership, but they do occasionally have clerics and clerical assistants.
Berserkers outfit themselves well as warriors, with swords, axes, and chainmail. They disdain ranged combat, preferring to charge into the thick of melee.
Berserkers usually make small, informal, mobile camps. Occasionally, they dwell in cave complexes, in ruins, or in fortified structures they've built (or comandeered) themselves. Berserker lairs often have prisoners and camp followers such as merchants (noncombatants).